What is this? Myrtle Beach find

[PSchleis]

No idea. Kind of reminds me of a sea urchin, but not quite. Also reminds me of the kind of "hat" an acorn wears. It's got a little peak to it. Animal? Plant? (Side view and better top view added below in a post.)

[Tidgy's Dad]

Shark dermal denticle? 

[Al Dente]

Broken piece of shark or bony fish centrum.

[PSchleis]

30 minutes ago, Al Dente said:

Broken piece of shark or bony fish centrum.

I definitely see how you came to that conclusion from the underside. I have several centrums. But this thing is only as thick as cardboard, and the topside has a very distinctive pattern to it. I can't find any samples of centrums that have that kind of feature on one side. Have you seen that sort of thing before?

[PSchleis]

Here's a better photo of the top, and a view of the side.

[sixgill pete]

I agree completely with Al Dente. Definately a broken piece of centrum. The part you are calling the topside, is the section you normally do not see. 

[Rockwood]

The in side.

[Darktooth]

The upside, down.