A Beginner's Guide to Shells
Limpets & Keyhole Limpets
- Approximately 35 species of Limpets live in North American waters.
- Conical shells may be smooth or ribbed, round or narrow at the base, and may reach 4 inches in diameter.
- Limpets living in turbulent wave areas have lower shell heights than those in calmer conditions. Limpets living among grasses have longer, narrower shells.
- Keyhole limpets have a hole or slit near the apex of their conical shell that sets them apart from true limpets.
- Look for a rounded aperture on these shells, which range in height from one inch to 4 5/8 inches.
- They are slender, variably sculptured, have convex whorls, and are almost always white in color.
- Some 95 species inhabit North American coasts.
- About 30 species of Ceriths are found on North American coasts in warm or temperate waters.
- Look for sculpted whorls decorating the exterior of these slender shells.
- The shells range in height from 1/8 inch to 6 inches with a pointed tip.
- About 140 species of Murex live in North America.
- Most have spines or ribs and a lengthened canal on one end.
- The shells can be elongated or round in shape.
- They range in size from one inch to 10 inches high.
- Eleven species of this mollusk are known to live in North American waters.
- Look for whorled shells with a short spire and a thick outer lip that can be either toothed or smooth.
- Twenty-five species of Olive shells are found in North America.
- Look for various patterns and fine wrinkles, with a smooth and shiny exterior.
- Most are whorled and cylindrically elongated with a small spire.
- Olive shells may vary from 1 inch to 5 inches in length.
- Nearly all of the 600 species of Cones around the world have a similar distinct design: a conical shape, flat top, and a slit-like lip running along its length.
- This shell’s body can be smooth or angled with rounded or pointed knobs.
- Cones can range in height from one inch to 8 inches high.
- These snail-like shells are common beachcombing finds on North American coasts.
- Moon shells vary in length from one inch to 5 inches.
- They're usually round, smooth and broad with short spires.
- Tiny Periwinkles range from 1/8 inch to 1 inches high.
- The solidly built shells are smooth, sometimes sculpted, and round to oval in shape.
- Of the 23 species known in North American waters, almost all live in intertidal regions.
- About 200 species of Whelks inhabit our waters from the arctic to the tropics.
- Whelks range in height from one inch to 8 inches.
- They may be smooth or have sculpturing lengthwise or spirally.
- Tropical species generally have thicker shells than their northern counterparts.
- Most of the 25 North American Turbans favor warm waters.
- Look for thick shells with a pearly interior and either a smooth or sculpted exterior.
- Turbans range from 1/8 inch to 12 inches wide.
- Approximately 180 species of Top shells inhabit North American waters.
- Look for spiral shells with variable exteriors and pearly-colored interiors.
- Top shells range in size from 1/8 inch to 6 inches in length.
- There are only 20 species of volutes living in North America.
- Look for elongated shells that range from one inch to 18 inches high.
- A deepwater species within this group called junonia is prized for its brightly colored shell.
Turret or Screw Shells
- There are 17 species of turret or screw shells inhabiting North American waters.
- These large shells are sized between one inch to 5 inches.
- Look for convex whorls and spiral coils, with a circular aperture.
- All 70 known species of Conch inhabit tropical waters. Three of the seven species found in the tropical western Atlantic may be found as far north as Florida.
- Shells of the American species are 2 to 12 inches high and thick, with an extended outer lip.
- Look for a series of spines on the last two whorls near the spire.
- Cowry shells are found in all tropical and warm waters, with six species living in the Caribbean, five in the southeast, and eight in western tropical waters.
- The cylindrical or oval shells range in size from 3/8 inch to 6 inches.
- Look for a smooth, shiny exterior with varied color patterns.
- About 20 species of Auger live in North American waters.
- Look for whorled, narrow, and elongated shells with smooth or ribbed grooves on their exterior surface.
- Auger shells range anywhere from one inch to 8 7/8 inches high.
- The plate that seals the mouth of the shell is pointed at one end and rounded at the other.