Plz Help Id Possible Tooth ( Dinosaur, Shark, ?) Found In Beach Water

[Heathertinnelle]

I found what I thought was a cool shaped piece of drift wood ( although it was sunk on the ocean floor), later looked at it closer to realize this was no ordinary object. It looks like petrified wood, but is hard like bone. It's lightweight, brownish in color, with iridescent vein-like webbing covering the outer surface. On the inside, it has hollow areas like tunnels that nerves or veins ran through. Although broken a bit on the top corner and worn some on both sides, I have a feeling that this is something prehistoric and significant. Any help would be much appreciated. I've googled everything I could possibly think of.

Edited August 19, 2013 by Heathertinnelle

[AgrilusHunter]

Second one of these we've had on the forum today! I think this is a sea robin skull plate. Good eyes to spot it and welcome to The Forum!

Edit: here is a link to the other specimen posted today.

Edited August 19, 2013 by AgrilusHunter