Clams

As I've said, this must be the season for many shells of the same kind to wash on shore. There are piles of these clams - I've always called them Razor Clams, but they may be Jack-Knife Clams. They are almost transparent. Clams are bivalves with both a front and back shell which hinge together. They have a foot which sticks out between the two shells and is used for burrowing into the sand and/or mud and for scooting sideways. They have 2 tube-like siphons on the opposite end which protrude. The siphons go to the surface and take in water full of planktons to "eat" and oxygen for its gills which are located by the foot.
These clams prefer to stay beneath the sand or mud, but can be uncovered by rough surf where starfish, snails, and crabs encounter a feast.
This picture is not large enough for you to see all of the other shells in and around these clams, but there are baby whelks, cockles, and coquina along with other various and sundry shells.

Sea Urchin Tests

Among all of the thousands of starfish on the beach are several Sea Urchin tests. The test is the shell-like portion of the urchin left when it dies. This one is, I think, a Purple Sea Urchin, even though the spines look black when you find one whole on the beach. The purple spine is a very dark purple. This dead starfish had it clasped tightly and I had to work to free it.
I'm assuming that the reason I found several of the tests is that the starfish had eaten them - a final meal, so to speak.
When alive, the urchin has neele-tipped spines covering the test.Most of the space inside the test of a sea urchin is devoted to storing unfertilized eggs. When the eggs are ripe, the female will shed hundreds of thousands of eggs. These are considered a delicacy in Japan and Greece, and are sold like ice cream in the Barbados.
The test is very, very fragile and so it is always fun to find an unbroken one.

Sand Dollars

Sand Dollars (the true name for these is "Keyhole Urchin") are fairly plentiful on the Isle of Palms, but are basically clustered in 2 places: around 52nd Ave in front of a hot pink house and further up towards the end of the island.. The ones at 52nd are typically already whitish and can usually only be found at low tide. If you're willing to walk in the water, you can often find 10-15 in one walk. The ones found further north, almost at the end of the island, tend to be alive. It is against the law to take a live sand dollar in SC, so when one is found, you need to turn it over and check to see if spines are moving. If not, it is dead and can be taken from the beach.

Sand Dollars are wedged/buried beneath the sand in beds which are parallel to the beach. The green-brown spines on the underneath are used for digging and are very short and the 5 petals on the top are hollow and used for breathing. The enemies of the Sand Dollar are starfish and flounder and so they burrow face first to escape these enemies and storms.

To get the white Sand Dollars that are found in stores, soak in 50% Clorox and 50% water and then set in the sun to finish the process.

On the left: live Sand Dollar. On the right: same type of Sand Dollar, dead and bleached by the sun