Urchin ID

This guy must have came out of my live rock. Strange part is I haven't added any in over two years. Any idea on what kind it is? Harmful?


Edit: So since the upload feature is not working, a photo of the urchin can be found here:

http://www.flickr.com/photos/47679413@N08/4365098081/

 

Looks kind of like... Strongylocentrotus purpuratus

http://en.wikipedia.org/wiki/Sea_urchin

 

i would guess pencil urchin but im not positive

 

Does look like a pencil

http://www.liveaquaria.com/product/aquarium-fish-supplies.cfm?c=497+530

I read... there are over 700 types

 

If it is a pencil urchin, that would explain where my cleaner shrimp went....

 

Did see F & S says... Reef Compatible = No

 

I doubt he had anything to do with the cleaner shrimp disaspearence, they don't move fast enough, however they are great! algae eaters, probably the best of anything out there. My urchin leaves the rock white as he goes over it. Now the pencil may also like some corals, depending on which pencil he is, I don't know. Just keep an eye on him and if you don't see any problems with the corals, I sure would keep him. How did he get in the tank??