What looks like an oyster, snacks on tiny ocean animals, and has lived in Earth's oceans for over 545 million years? It's the brachiopods! These creatures are still around today. And they are sometimes confused with other shelled animals, like clams, because they look so much alike. One of the biggest mass extinctions of all time killed off most species of Brachiopods 250 million years ago.

Image credits: main image, © AMNH; stumper, © AMNH.