Features in the Life History of the Ribbed Clam (Paphia staminea). 1-Large adult specimen in its seventh season. 2-Young clams in the middle of their first season. 3-Young clam in its second season. 4-Clam at the beginning of the sixth season. 5-Clam at the middle of the third season. 6-Clam in its fourth season. 7-Clam at close of its fourth season. 8-Clam at close of its sixth season. 9-Clam at the middle of its third season