National Megalodon Day is observed on June 15 and celebrates the megalodon, the largest shark known to have existed. This prehistoric predator, an ancestor of modern sharks, is believed to have dominated the oceans millions of years ago, growing up to 60 feet long. The day encourages exploration and appreciation of marine life and Earth's prehistoric past through various activities. Common customs include visiting maritime museums to view megalodon fossils, hosting movie marathons featuring documentaries about these ancient sharks, and organizing trivia nights focused on sharks. Additionally, participants may create megalodon-themed art or read literature about prehistoric marine life. The event was initiated by the Aurora Fossil Museum in North Carolina to raise awareness of the megalodon's significance in marine ecosystems.