I borrowed these first two images from the Internet. I hope the owners won’t mind. I couldn’t find a name to give credit to.
These are horse clams. I’ve heard they make a tasty chowder, but they can be very chewy if not prepared properly. I think the idea is that after a lot of work to clean them of grit and sand, and taking the stomach contents out, you can either grind the meat or pound the dickens out of it and cut it small before frying the pieces – quick and hot – like you would octopus or abalone.
My only experience with trying to cook horse clams happened many years ago, before I knew how tough they could be. I gave up after several minutes of not being able to chew through the first piece. Horse clams are probably named for their large size (see the ruler under the photo of the clams), but I’ve heard that even the smallest of that family will give your jaws a good workout.
Now that I’m older and wiser, I might try again, doing it the right way (but I’d have to be desperately hungry).
The diagram below shows the foot of the clam (on the left). The clam uses this for digging down into the sand. The siphon (on the right) has intake and outflow tubes. When the clam is digging down into the wet sand, the siphon helps it move along with its “water jets.” In the photo below, taken by the Captain, right into the sun, he has nevertheless captured the horse clam action. If you look closely you can see the water squirting about two feet into the air as the horse clams frantically dig to hide from him. Actually, the tide has been going out and the clams don’t want to be left “high and dry.” (Now you can see where that expression came from.)Do you see the squirts of water going into the air all along the beach? It’s almost as tricky as running through a sprinkler to walk along this beach. Be prepared to get your legs wet.