Some sort of sea clam thing?

Question

Okay, so we were at the shallow part in the ocean and we see a little rock thing with what seemed like barnacles on it. Immediately my puppy ran to investigate.

As soon as he touched it, it sprayed a big jet of water, and buried deep in the sand. Does anyone know what this is?

10 points.

Answer 1

It was likely some type of clam.  There are welk clams, turkey clams, lion paws, etc...the list is nearly endless. Some can be as large at 12" long clam.  They burrow and jet water and are usually found in the shallows and can be exposed at low tide.