The Oldest Part of the Bivalve Shell is The

Question

The oldest part of the bivalve shell is the
A)umbo.
B)periostracum.
C)hinge ligament.
D)left valve.
E)right valve.

Accepted Answer

The umbo is the oldest part of a bivalve shell because it is the initial point of growth for the shell and is located at the central peak of each valve. As the bivalve grows, the shell material is added to the sides of the umbo, causing it to become more and more distant from the center of the shell.