A Beginner's Guide to Shells

Are you a seashell novice? Use our helpful guide to figure out what you've found.

Limpets & Keyhole Limpets

Photographer: Jean Allsopp

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.

Wentletraps

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Wentletraps

  • 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.

Ceriths

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Ceriths

  • 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.

Murex

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Murex

  • 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.

Helmet Shells

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Helmet Shells

  • 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.

Olive Shells

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Olive Shells

  • 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.

Cones

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Cones

  • 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.

Moon Shells

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Moon Shells

  • 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.

Periwinkles

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Periwinkles

  • 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.

Whelks

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Whelks

  • 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.

Turbans

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Turbans

  • 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.

Top Shells

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Top Shells

  • 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.

Volutes

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Volutes

  • 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

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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.

Conch

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Conch

  • 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

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Cowry

  • 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.

Auger

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Auger

  • 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.

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