urchin ID- good or bad guy

[marino420td]

I recently discovered this dude in my tank. Any idea what type of urchin this is? Is it reef safe?

http://i16.photobucket.com/albums/b39/marino420td/IMG_3817.jpg

It is about the same diameter as a nickel.

[greenbean36191]

It's hard to tell, but it looks like it might be a very young Echinometra or rock boring urchin. It will probably grow to be about 4 inches across the spines.

Most urchins are safe but almost all will occasionally nibble on something meaty (sometimes corals). This guy doesn't appear to be one of the exceptions that aren't safe in a reef.