Mytilimeria nuttalli

Unlike most clams that live in sandy or rocky substrates, Mytilimeria nuttalli clams are usually embedded in colonies of compound ascidians with only their siphons exposed.^[3] Larvae settle on the ascidian colony and eventually become surrounded, except for a narrow slit for the siphons.^[2] Because the shells are protected under the surface, they are thin and fragile,^[3] and often crack when dried.^[2] If they are removed from their ascidian hosts, the periostracum tends to peel from the shell.^[4] The shell tends to be around 2 cm, but can reach 4 cm in length, and have a pearly interior.^[2][3]