A giant clam in Kiribati's Phoenix Islands exhibits the striking colors of its mantle.

A cross-section of a nautilus shell in Boston shows the spiral of chambers, called camerae, that this cephalopod builds for itself as it grows.

A scallop near the Galápagos Islands shows off its brilliantly colored mantle and the blue dots that are its multiple eyes.

The dark center of a moon snail's shell gives it its other common name: shark eye snail. This specimen was found in Cape Cod, Massachusetts.

Giant clams, like this one in Papua New Guinea, get their wild coloring from the billions of algae they host in their mantles.

Scallops await sale at the Rialto Market in Venice, Italy.

A close view of a giant clam in Sabah, Malaysia, reveals the intricate patterns and textures of its mantle.

Harvested cherrystone clams sit in a pile.