what is this

[trickle25]

what is this ? i was changin around my LR and i saw this crawin around on the bottom of one of the LR.. should i leave it alone or kil it ?

 

[sterling]

The pic is kind of fuzzy, but looks like an urchin. Leave it. Good thing.

 

[trickle25]

it looks kinda creepy like somthing from hell raiser...will it attack my fish or anthing like that ...i dont know how it got in the tank ive never bought anything like it

 

[timo]

It most likely came on your rock, nicknamed a "hitchhiker".

 

[leigh]

Yeah, looks definitely like an urchin. they are quite benign algae eaters--however they will eat coraline...

 

[lionstorm]

mine doesn't eat coraline. I know they will eat CORALS but doubt they eat coraline algae.
Urchins are quite good additions to a tank, I have a pencil sea urchin about the size of baseball in my tank and he does a great job.

 

[trickle25]

well iv e got a few mushrooms, polps and a few other corals so i should get ride of it cause it will eat my corals

 

[leigh]

Actually it is well known that they can eat coraline. Most people, however, do not worry about this long term as often by scraping the coraline off the rock they spread spores, so while they eat and scrape off some, they in the big scheme of things, help coraline to spread. They do munch on some corals, but it's really hit an miss...some do, some don't. If you like him I'd say keep him until you see/know he's causing a problem. The only other thing to keep in mind with urchins is they can really smush themselves into any little crevice and so often manage to tumble rockwork in tanks. If you choose to keep him make sure your rocks are secured/stable. Hope that helps, -leigh
Oh, and btw, there are a few of them that have venomous spines (nothing severe, kinda like a bee sting)...so before you go grabbing it if you choose to remove it you may wish to post a clearer pic or do a web search to really nail down which type of urchin it is.