Scientists have found that a chameleon is able to rapidly change color because of tiny crystals directly under the skin that act as mirrors.

In a study published Tuesday in Nature Communications, researchers shared that panther chameleons have crystals called iridophores that contract or expand if the chameleon is feeling excited or stressed, and reflect different wavelengths of light. "Light will bounce on them only for specific wavelengths," co-author Michel Milinkovitch told BBC Earth. "The other wavelengths will not bounce on these cells."

The different colors are caused by the size of the crystals and where they are on the skin. Male chameleons change color frequently to show off for a rival or to scare him away. "It's really a social display," Milinkovitch said. The researchers also found a deeper layer of skin that reflects near-infrared sunlight, and might be responsible for helping chameleons regulate body temperatures. Catherine Garcia

Russian national Maria Butina will plead guilty Wednesday to working as an unregistered Russian agent "to establish unofficial lines of communication with Americans having power and influence over U.S. politics," with help from her American boyfriend, Republican operative Paul Erickson, and under the direction of Kremlin-linked banker Alexander Torshin, according to a draft plea agreement obtained by ABC News. "Butina sought to use those unofficial lines of communication for the benefit of the Russia Federation."

A 30-year-old purported gun-rights activist, Butina has been in jail since her arrest in July. She signed the plea deal on Dec. 8, and according to CNN, she is already cooperating with federal prosecutors in Washington, D.C. According to the plea deal, Butina said she and Erickson (identified as U.S. Person 1) drafted a proposal in March 2015, later sent to Torshin, in which she wrote she'd already "laid the groundwork for an unofficial channel of communication with the next U.S. administration," which she predicted would be Republican.

Butina traveled the U.S. and met with Republican presidential candidates in 2015, and in December of that year, she helped arrange a trip to Moscow for senior NRA leaders and donors, pushing them to meet with senior Russian officials, including Foreign Minister Sergey Lavrov and Dmitry Rogozin, a deputy to Russian President Vladimir Putin. After that trip, according to U.S. prosecutors, Butina sent Torshin a message, translated to read: "We should let them express their gratitude now, we will put pressure on them quietly later."

Erickson, who's also reportedly a target of federal prosecutors in Washington, wrote an acquaintance in October 2016 that he has "been involved in securing a VERY private line of communication between the Kremlin and key [unnamed political party] leaders through, of all conduits, the [unnamed gun-rights organization]." On MSNBC Monday night, Rachel Maddow connected some speculative dots between the NRA, Russia, and the Trump campaign, and she noted Torshin's sudden "retirement." Watch below. Peter Weber

In a 13-minute address to France on Monday evening, an unusually contrite President Emmanuel Macron laid out some new "strong measures" to address the "economic and social emergency" gripping the country, exposed by four weekends of "yellow vest" protests. Macron said his government would pay for a 100 euro monthly raise in the minimum, eliminate taxes on overtime pay in 2019, cut an "unjust" tax on small pensions, and ask profitable companies to give workers a tax-free bonus this month. He also said he would travel France to begin a dialogue with mayors, regional civil leaders, trade unions, and other stakeholders in France's success. He did not pledge to reinstate a special tax on the richest French citizens.

It is unclear if Macron's concessions, following his scrapping of a planned fuel tax, will defuse the yellow vest protests. Protest leaders said they would continue taking to the streets, but some analysts said they expect the movement to fizzle as Christmas approaches. It's also unclear how France will pay for the proposals, estimated to cost $9 billion to $13 billion. As notable as Macron's fiscal proposals, however, was his uncharacteristically soft tone. "I take my share of responsibility" for the anger roiling France, Macron said. "I might have hurt people with my words." Peter Weber

Stephen Colbert began Monday's Late Show by congratulating outgoing White House Chief of Staff on his imminent departure and for "a job, well, done." President Trump, who had a tense relationship with Kelly from the start and promptly broke his promise to let Kelly break the news of his departure, "already had Kelly's replacement picked out," Colbert noted. But his pick Nick Ayers, turned him down, "and it's not just Ayers — nobody seems to want this job."

"So the president is in desperate need of a chief of staff, and he's got no viable candidates, which is why I'd like to take this opportunity to officially throw my hat in the ring," Colbert offered. "Mr. President, I, Stephen Colbert, am your next White House chief of staff." He said he wouldn't be able to control Trump or bring order to the chaotic West Wing, and he will fight with Trump and disagree with his policies, "but I believe in my heart of hearts that this could be fun for me," Colbert said. "I mean, who would pass up the chance to spend 10 minutes on the deck of the Titanic while it's sinking?"

"I think it's fair to say that being Trump's chief of staff did not work out well for John Kelly," Trevor Noah said on The Daily Show. "Because remember, he came into the job known as a respected four-star general, and now he's leaving the job known as the guy who fired Omarosa." In fact, there's a good reason "nobody wants this job," he said. "We all know by now what happens if you work for Trump. At some point you're going to lose your credibility, and then you spend every day being insulted by a 72-year-old 5-year-old. Who would want that? So many Americans don't want this job, Trump might have to let a Mexican do it." Except Michael Kosta volunteered, too. Watch below. Peter Weber

The Trump administration will formally start the process of lifting federal Clean Water Act protections for millions of acres of wetlands and thousands of miles of streams across the U.S., undoing decades of protections against pesticide runoff, industrial waste, and other pollutants. The proposed rules, to be unveiled by the Environmental Protection Agency as soon as Tuesday, are a victory for agricultural and real estate interests but could degrade the drinking water used by tens of millions of Americans and endanger fisheries and the habitats of migratory birds and other species.

President Trump promised during his campaign to roll back the Obama-era Waters of the United States rules, an expansion of federal protections under the the Clean Water Act of 1972, but the new proposals target protections dating back to the George H.W. Bush administration or earlier. The Trump rules, which will be subject to 60 days of public comment, will keep protections for larger bodies of water but remove federal safeguards for wetlands not adjacent to navigable waterways plus most seasonal streams and ponds. The newly vulnerable streams provided drinking water for as many as 1 in 3 Americans, especially in the arid West, according to scientific studies used by the Obama-era EPA.

The Trump EPA calls that data incomplete and will argue that it is tackling an Obama-era federal power grab against rural farmers. Trump's promise to end the Waters of the United States policy was cheered by farmers, real estate developers, golf course owners, and mining and oil firm. Environmental groups call the new proposal a disaster. "It is hard to overstate the impact of this," Blan Holman, managing attorney at the Southern Environmental Law Center, tells the Los Angeles Times. "This would be taking a sledgehammer to the Clean Water Act and rolling things back to a place we haven't been since it was passed. It is a huge threat to water quality across the country, and especially in the West." Peter Weber

A California woman forced to abandon her dog in the Camp Fire came back almost a month later to find he had survived and was waiting for her the whole time.

Andrea Gaylord's two dogs, Madison and Miguel, were left behind when residents of Paradise received an evacuation order since she wasn't able to retrieve them as the fire spread; the K9 Paw Print Rescue group writes that she "hoped and prayed" they would be okay. A volunteer was able to find Miguel, and another left food and water out for Madison, CNN reports.

Gaylord was naturally anxious to return home, and when she was finally allowed to do so this week, she found Madison sitting right there on the property weeks later, even as the home had been completely destroyed, reports USA Today. "Imagine the loyalty of hanging in in the worst of circumstances and being here waiting," Gaylord said. "It was so emotional." Brendan Morrow

Accused Russian spy Maria Butina may be about to plead guilty.

Butina's attorneys on Monday filed a request for her to withdraw her previous plea of not guilty, The Washington Post reports. CNN writes that she looks to have reached a plea deal with the Justice Department, although any further details, including what she would be pleading guilty to, are currently unclear.

Five months ago, Butina was arrested and charged with one count of conspiracy and one of acting as an agent to a foreign government. She has been accused of spending years attempting to influence American policy by forging relationships with prominent conservatives, including with the National Rifle Association, while keeping in contact with Russians, per CNN. Butina's lawyers have argued that she was simply interested in improving Russia's relationship with the United States, The Associated Press reports. Her arrest was not a part of Special Counsel Robert Mueller's investigation into Russian interference in the 2016 election.

However, The New York Times reports that any plea deal would likely require cooperation with ongoing investigations, leaving open the possibility that she could provide them with some key information. Brendan Morrow