The Truth About Beaversharks
There is no such creature as a "beavershark." Beavers and sharks belong to entirely different branches of the animal kingdom. Beavers are rodents, while sharks are fish. They differ fundamentally in their biology, habitats, and behaviors, so a hybrid between the two does not exist in nature.
If you encountered the term online or in conversation, it is likely a fictional creation, a joke, or a misunderstanding rather than a real animal.