You might think that most facts about clams are boring, but clams are actually quite remarkable! The name clam can be used in reference to a number of mollusks, mussels, and oysters. For the most part, clams are masses of tissue and are completely invertebrate—meaning they have no bone structure. Instead of bones, clams of all sorts have some form of shell to protect them from the elements and predators such as birds, fish, and humans. In the science world, clams are known as bivalves—which basically means two-shells.