Mermaid's Purse - Every child who's ever walked a Bay State beach has wondered about this rubbery, black casing with double digits extending from either end. Known as a "mermaid's purse," it is actually an egg case from a skate. Upon careful examination, you may even be able to find the small opening where the baby skate emerged.

Northern Moon Snail - This large, predatory snail (Euspira heros) lives on sandy bottoms in the subtidal zone and inspires curiosity in beachcombers by leaving behind sandy collars frequently found in the shallows. These rubbery, circular formations are the snail's egg cases.

Channeled Whelk - Like the moon snail, this predatory gastropod of the sandy subtidal (Busycon canaliculatum) leaves an egg casing for the imaginative to contemplate—this one looking like a curling, rubbery backbone.

Sand Dollar - Another common inhabitant of sandy bottoms, Echinarachnius parma are deep red to an almost-black purple, covered with fine hair-like spines when alive. Once dead, they lose the spines and this coloration, going gray, until washed onto the beach. In the heat of the sun, they bleach to a beautiful bone white.

Slipper Shell - Like the name implies, the shells of Crepidula fornicata look something like inside-out slippers—an outside cup with an inside shelf extending halfway over the bottom. They attach to hard surfaces, often to the outside of other mollusk shells or rocks. They are also found stacked on top of each other in a mating embrace complete with a sex-change twist—the slipper shells on the bottom become female, the ones on the top become male, and the ones in the middle are hermaphroditic.

Lady or Calico Crab - Although Ovalipes ocellatus does bury itself in sand, unlike many other crabs in this region, it can swim using paddle-like back legs. This aggressive and fast moving crab has a pink, mottled carapace (i.e., shell) with a delicate scalloped edge.

Jingle Shell - Also known as Mermaid's toenail, Anomia simplex may be most commonly known as a component of wind chimes, with these light-weight shells making pleasant tinkling sounds when hit together. After big storms, the beach is littered with windrows of jingle shells, with their distinct curved top shell and flat bottom complete with hole for byssal threads to attach to a solid object. The glossy, semi-translucent shells come in a variety of colors: silver, yellow, orange.

Razor Clam - Commonly known for its unusual shell, shaped like an old-fashioned razor, Ensis directus is one of the fastest burrowers in the clam world. Although rarely found on any menu, its meat is edible.

Bay Scallop - Giving new meaning to “old blue eyes,” Aquipecten irradians has a row of bright blue eyes that line the edge of each shell. It is also an accomplished swimmer, using its powerful adductor muscle (the only part of the scallop that we eat) to flap its two shells together. By directing the resulting current, these mobile shellfish can move in almost any direction.