piddock clam burrow in eocene turtle shell

[Plax]

Seems like the subject of piddock clam burrows comes up here on occasion. I found this interesting example of a clam burrow that was in the hard ground at the top of the New Hanover Member of the Late Eocene Castle Hayne formation. The clam had apparently burrowed through the indurated conglomeratic limestone including the turtle shell. It's a bit difficult to discern in the pics but the sediment is burrowed as well as the shell so the burrowing happened in the hard ground, not in the turtle shell. The result is a half circumference burrow. If not for the bored sediment one could make a case for the shell being burrowed on the sea floor prior to fossilization (in the dead turtle shell). Googling "gastrochaenolites" gives some really good pics and info.