Gastropods are spiral.

Brachiopods are symmetrical. The bottom shell has a different shape than the top shell.

Bryozoans look like chicken bones.

Trilobites were the "cockroaches" of the ancient oceans.

Crinoids look like Cheerios when they are separated from their stems.

Horn coral comes to a point. Lines in the fat end meet in the center.

Pelycipods are shells which have identical top and bottom halves.