Sea Shells by the Sea(Gulf)Shore: How To Identify Your Shells!

One of our favorite pastimes is walking the shoreline and picking up shells. There are so many unique varieties that wash up on our shore, and it’s always interesting to know which ones you’re looking at. Use this quick guide to identify popular shells found on our beaches.


Ponderous Ark Seashell1.) Ponderous Ark: This shell is very thick and heavy for its size. It has distinct radiating ribs (usually about 30) and the rear margin of the bivalve slopes down from the hinge/beak area. The off-center, very prominent beak points toward the rear of the shell. The hinge has comb-like teeth, which are visible along the length of the hinge line. The shell may reach a length of 2½ inches.


2.) Heart Cockle SeashellVanhyning’s Heart Cockle: This bivalve is a pretty specimen. Its outline is more or less like a lopsided triangle as you look down at the exterior of the shell, though the ribbed shell is well-inflated. It can be over 5 inches in length and has distinctive chestnut-colored bars on its yellowish-tan-white surface.


3.) Crowned ConchCrowned Conch: A univalve which is 2 to 5 inches tall. The shell is dark brown or almost black, with rather random bluish-white or yellow spiral bands of color. The smooth form of the shell has small spines on the upper whorls; the non-smooth form has longer, larger spines on the upper part of the shell, and some additional sharp spines in the area of the flaring aperture. The overall shape of the shell is pear-like.


4.) Oyster ShellOyster Shell: Oyster shells may reach a length of three inches. Each half of the bivalve is shaped something like a notched wing. One valve of the pair is a little more inflated than the other. The posterior end of each valve is longer than the anterior. The outer edge of the posterior margin is rounded. The hinge line is quite straight.


5.) Shark's EyeShark’s Eye: The Shark’s Eye (or Atlantic Moon Snail) is a bluish gray-brown color with a dark “eye” at the tip of the spire. It might be as much as 3 inches in diameter. The living snail is rather amazing looking, for it has a foot that extends far out all around the shell.


6.) Calico Scallop: These pretty bivalves live in shallow water. TCallico Scallophey may reach a length of 2 inches. The surface of a Calico Scallop shell has about 20 rounded radiating ribs and numerous subtle growth lines that run from the beak area of the shell outward. Color patterns on this clam are diverse and beautiful — dark maroon, rose, purple, brown, orange — on a white surface. Usually the upper half of the bivalve is more colorful than the lower. The wings or ears of the scallop are about equal in size.


7.) Cross-Barred VenusCross-Barred Venus: This sturdy and distinctive little clam shell is marked by radiating and concentric lines, giving it a miniature lattice-work appearance. The slightly inflated shell is whitish often with often brown markings. On the inside of the shell is a central white area where the mantle of the mollusk was attached, and on each side of the mantle area are two somewhat round areas to which were attached the adductor muscles. On the hinge of the shell there are two “teeth.” The outer edge of the shell is finely ridged.


8.) Elegant DosiniaElegant Dosinia: The Elegant Dosinia is a lovely white bivalve that may reach a diameter of 3 inches. Its surface is marked with numerous uniformly-spaced concentric ridges. The Elegant Dosinia is almost circular in shape, except for its small beaks, which point anteriorly. The bivalve is very compressed — that is to say, the two halves of the bivalve fit together rather flat, almost like a ladies’ compact. The periostracum, or shell covering, is translucent, grayish, and varnish-like. If you scoop these at the waters-edge and lay them right back on the wet sand, they’ll sometimes burrow back below the surface! A fun thing to learn for all ages!


9.) Sand DollarsSand Dollars: Sand Dollars are approximately 3-inch, cookie-shaped creatures that live near shore in the sand in crowded beds, lying parallel to the beach. Soft “fur” on these creatures varies in color. Northern Sand Dollars are reddish-purple and brownish, while the southern ones are silver gray, tan, yellowish or greenish-brown.The Sand Dollar has what looks like the outline of a five-petalled flower on its top side. Be on the lookout for whole Sand Dollars, even when you are in the Gulf! It makes for a fun family activity on the beach. But be careful! These shells can be very delicate.


Skate Egg Cases10. Skate Egg Cases: The Skate egg case is a small (3-4 inches long), leathery, rectangular sort of pouch with long, thin, horn-like projections sticking out from each corner. The egg cases are made of keratin, the same substance that comprises human fingernails. An egg case forms around each individual skate embryo just before the mother deposits the cases on the sea floor. Locals refer to these at a Mermaid’s Purse!


Thank you to Seashells from the Ocean’s Edge Pictorial Index for helping us create this seashell guide.