Yellow goiter sponges, such as this Heterochone calyx on Pioneer Seamount, can grow to well over 3 feet across. Like most sponges, they eat by filtering microscopic bits of debris from the seawater that flows past them. MBARI researchers often see “forests” of sponges on the upper portions of seamounts, where eddying ocean currents may concentrate food particles. Even after large sponges die, their skeletons may survive for years on the seafloor.