Resilium

In anatomy, a resilium is part of the shell of certain bivalve mollusks. It is an internal ligament, which holds the two valves together and is located in a pit or depression known as the resilifer.

The hinge area in one valve of a scallop shell (Pectinidae), showing the space for the internal ligament, known as the resilifer

The resilium is part of the hinge mechanism in certain taxonomic families of bivalve shells, such as oysters and scallops.^[1][2][3] A resilium (and the resilifer, its associated contact point) is the primary structure comprising the type of bivalve hinge that is known as an "disodont" hinge.