Need help to identify

[TonyTPA]

Just saw this critter in my 11 month old tank 65 gal have not added any coral or fish in 5 months
It is black with white tipped spins. See pic

 

[BloopFish]

Seems like a type of rockboring urchin.

 

[TonyTPA]

is that a good critter or a bad one?

 

[BloopFish]

is that a good critter or a bad one?

Will eat all sorts of algae, even macro and coralline. It's a good critter, generally speaking.

 

[TonyTPA]

Thank you for the information, it must have been growing hidden for some time this morning was the first time I have seen it in the tank and as I said I have not added anything new to the tank in more then 5 months.

 

[BloopFish]

Thank you for the information, it must have been growing hidden for some time this morning was the first time I have seen it in the tank and as I said I have not added anything new to the tank in more then 5 months.

That's probably it. I've had baby urchins the size of a dime get even larger than the one in your pic within a span of several months before.