What is "requienia"

Requienia is an extinct genus of fossil saltwater clam, a marine bivalve mollusk in the order Hippuritoida, family Requieniidae. These rudists lived in the Cretaceous period, from the Valanginian age (136.4–140.2) to the Campanian age (70.6–83.5 mya). They were stationary intermediate-level suspension feeders.