Welcome to the Barn Catch em.
Surf clams break down into three parts. One is the tongue. Thats the large muscle that the clam uses to dig into the sand. The next is what is called salvage. It's the strap, abductor muscle, siphon and so on that are chopped up for clam chowders. Third is the belly. It's just that. The entire digestive tract and internal organs. It's green and brown and it's wrapped nice and neat in a thin skin. About the size of a golf ball and the juciest part of the clam. It's the first part a fish will go for.
They can put out a scent trail that can overpower anything else you want to chum with. Hope that helps you out and again welcome to the BARN.