President Trump's appointment of Matthew Whitaker as acting attorney general is already facing a legal challenge.

The state of Maryland is preparing to ask a federal judge to declare Whitaker's appointment illegal. This would mean Rod Rosenstein would be declared the legitimate acting attorney general, The New York Times reports. Plaintiffs argue Trump cannot "bypass the constitutional and statutory requirements for appointing someone to that office," and they are seeking an injunction.

Critics have taken issue with the fact that Whitaker did not receive Senate confirmation before being appointed as Jeff Sessions' replacement at the Justice Department. Others have argued it's constitutional for Trump to fill Sessions' role with someone who was not confirmed by the Senate, so long as it's on a temporary basis. Whitaker has been an outspoken critic of Special Counsel Robert Mueller's investigation into Russian interference in the 2016 election, and many have called for Whitaker to recuse himself from that investigation.

The court challenge is part of an unrelated Affordable Care Act lawsuit brought by the Maryland attorney general in which Sessions is named. The judge, Ellen L. Hollander, needs to replace Sessions as a defendant with his successor, which requires her to determine whether Whitaker is actually Sessions' legal successor, the Times reports.

If the judge rules Whitaker's appointment is illegal, the case would likely head to the Supreme Court, per NBC News. Brendan Morrow

Every time Avery Fauth, her two sisters, and her parents visit North Topsail Beach in North Carolina, they scan the sand, hoping to spot an ancient megalodon shark tooth.

The family kept up their tradition while at the beach over spring break. As they walked along, Fauth, a middle school student from Raleigh, saw something that caught her eye. Intrigued, she went to the object, which was buried in the sand. "I uncovered it and it keeps coming, and it's this big tooth, and then I hold it up and I'm screaming for my mom," Fauth told WECT.

It was a megalodon shark tooth, and her father, who started searching for megalodon teeth 25 years ago and got his daughters hooked on the hunt, was stunned. "I was really shocked and excited for her that she found something that big," he said. The megalodon, the largest shark ever documented, went extinct millions of years ago, and Fauth's tooth could date back three million years. "They're really rare to find and they're some pretty big teeth and they're pretty cool," she said. The tooth will live in a "special box" inside Fauth's home. Catherine Garcia

After creating a replica of the Iron Throne from Game of Thrones, welding student Michael Hayes can tackle anything.

The Louisville, Kentucky, resident attends the Knight School of Welding. Ahead of his wedding, the Game of Thrones fan decided to make the ultimate gift for his soon-to-be wife: an Iron Throne. He enlisted some of his instructors to help him, and over the course of two months, they cut out 400 aluminum swords for the 200-pound throne.

It took nearly 110 hours to complete the throne, which became the centerpiece of Hayes' wedding. His new wife, Kacie, was impressed not only by the throne, but by how much work Hayes put into the project. "The show is one of the first things my wife and I bonded over," he told WLKY. "It's a really important thing for us." The Knight School of Welding funded the $7,000 project, and it's now renting the throne out to fans holding watch parties and Game of Thrones-related events. They're sitting on something special: Instructor Anthony Williams says the throne is even more authentic than the one used on the show, which is made of fiberglass. Catherine Garcia

Secretary of State Mike Pompeo is planning on telling allies Japan, South Korea, and Turkey on Monday that the United States will begin sanctioning them if they keep importing Iranian oil, three U.S. officials told The Associated Press on Sunday.

After the Trump administration pulled the U.S. from its 2015 nuclear deal with Iran, eight countries who received oil from Iran were granted sanctions waivers and told they needed to start looking for alternate energy sources. Greece, Taiwan, and Italy have all stopped importing oil from Iran, but Japan, South Korea, Turkey, China, and India have not, and the waivers expire on May 2. Turkey has been vocal about the fact that it needs Iranian oil to meet its energy needs, with senior officials urging the U.S. to reconsider, AP reports.

President Trump decided on Friday not to extend the waivers, as a way to pressure Iran, officials said. It's unclear if sanctions will start on May 3 if the countries do not immediately stop importing the oil. Catherine Garcia

Comedian Volodymyr Zelensky plays the president on TV, and will soon take on the role in real life, too.

Exit polls show that Zelensky won Ukraine's presidential election on Sunday in a landslide, with 73 percent of the vote. Zelensky, 41, has no previous political experience. He handily beat incumbent Petro Poroshenko, who has conceded defeat.

On the show Servant of the People, Zelensky plays a teacher who accidentally becomes Ukraine's president. Ukraine is at war in its eastern Donbass region, and critics worry that because of his lack of experience, Zelensky, who has ties to billionaire oligarch Ihor Kolomoyskyi, won't be able to stand up to Russia or make peace with separatists. Catherine Garcia

President Trump's personal lawyer Rudy Giuliani made the talk show rounds on Sunday to defend his client following the release of Special Counsel Robert Mueller's report on 2016 Russian election interference and the Trump campaign's conduct surrounding the meddling. The former New York City mayor wasn't exactly cautious when responding to questions from Fox News' Chris Wallace, CNN's Jake Tapper, and NBC's Chuck Todd. Here are three of Giuliani's boldest opinions on the Mueller Report.

Info sharing is a-okay — Giuliani told Tapper on CNN's State of the Union that "there's nothing wrong with taking information from the Russians," saying that campaigns get information on their opponents from so many different sources.

On NBC's Meet the Press, Giuliani told Todd that using material stolen by foreign adversaries in a campaign isn't fundamentally a problem — it just depends on the material itself.

Interference didn't do much anyway — While speaking with Todd, Giuliani — who said that much of the Mueller report is questionable — argued that it's "hard to believe" Russian interference did much to sway the 2016 election. While there is no way of quantifying the interference's tangible influence on the vote count, even members of the Republican Party, such as Sen. Marco Rubio (R-Fla.), expressed serious concern over the amount of Russian interference the investigation uncovered.

Trump had reason to fire Mueller — Much of the analysis on the Mueller report points to aides such as former White House Counsel Don McGahn preventing Trump from "influencing" the investigation and, therefore, obstructing justice. But Giuliani told Wallace that even if Trump had fired the special counsel, it would not have been obstruction. Giuliani's point was that Trump had good reason to replace Mueller because he hired "very, very questionable" people to investigate Trump. Tim O'Donnell

To impeach, or to not impeach? That is — always, it seems — the question.

Rep. Jerrold Nadler (D-N.Y.), the chair of the House Judiciary Committee, told NBC's Chuck Todd on Sunday's edition of Meet the Press that he is not ruling out beginning impeachment proceedings against President Trump following Special Counsel Robert Mueller's report on 2016 Russian election interference and the Trump campaign's conduct surrounding the meddling.

Nadler was anything but surefire on the matter, though. Per The Hill, he said Congress would first have to receive an unredacted version of Mueller's report — for which Democrats have issued a subpoena already — as well as hear testimony from both Mueller and Attorney General William Barr before determining whether to begin proceedings or not. That said, Nadler added that "if proven," some of the material from the Mueller report, particularly possible obstruction of justice, would be impeachable.

Nadler is not the first prominent Democrat to discuss beginning impeachment proceedings in recent days. Sen. Elizabeth Warren (D-Mass.), a presidential candidate, did so on Friday, while Rep. Adam Schiff (D-Calif.), the House Intelligence Committee chair, said during Sunday's This Week that Democrats may undertake impeachment, even with the knowledge that the Senate would be unlikely to vote Trump out of office. Schiff called the Mueller investigation "more significant" than Watergate. Tim O'Donnell