Shark tooth?

[Jen0622]

Was recently in Costa Rica and found these on the beach. Have found many black sharks teeth in the Carolinas but wasn’t sure if these were also? Any info would be greatly appreciated. TIA

[fossilnut]

Possible silicified sponge spicules.

[Fossildude19]

These remind me of parts of an echinoid 's Aristotle's lantern.

What size are these?

[marfijak]

These are modern burrfish spine bones. I have found them before.

[marfijak]

[Al Dente]

I think it is more likely porcupine fish, they have longer spines than burrfish.

[marfijak]

There are a couple different varieties and lots of people use the common names interchangeably so who knows. However, on your bones, the longer spines are the interlocking pieces (think tripod) and the shorter nubs are the spines that stick out of the fish.