What is this?

[Cardinal Tetra]

Last week I brought back some sponge I found at Sentosa beach, and placed it in my tank.

Few days later I discovered this snail like creature on the sponge. It is white in colour with blue spots, exactly the same colour as a blue spotted ###### shrimp. It has 4 smaill spikes on its back like a sea urchin.

Anyone knows what it is? Here is a picture of it, its kinda blur, but its the best shot I could take.

[Cardinal Tetra]

I will have to attach the NON RESIZED PIC as its much clearer.

[Qxnviolet]

Looks like a nudibranch to me.....btw, the smaller pic is clearer...

[Panzz]

it does look like one of those parasitic slug or snail that will do some damage to your corals, best is that you have a better pic so we can get a better id rather than guessing.

[Qxnviolet]

Yeah, a clearer pic would be great...but it sures looks like a nudi or sea slug. Really looks like a certain sea slug i've seen retailing at LFS before.

[Cardinal Tetra]

Well I guess it wouldn't do much harm since its a FOWLR tank. It could be a nudi, and its really familiar but just can't recall where I've seen it too.

[Panzz]

a possible guess it a sea rabbit.

[FionaFiona]

Last week I brought back some sponge I found at Sentosa beach, and placed it in my tank.

Few days later I discovered this snail like creature on the sponge. It is white in colour with blue spots, exactly the same colour as a blue spotted ###### shrimp. It has 4 smaill spikes on its back like a sea urchin.

Anyone knows what it is? Here is a picture of it, its kinda blur, but its the best shot I could take.

That look like a nudibranch to me. Refer to:

Nudibranch Adoption Thread

from the thread, the picture and description posted by killerwhale... it looks similar.

If its REALLY ( and i guess MOST PROBABLY) is a nudibranch, below are what I learnt from bro Elune:

1) it feeds on sponges; thats why it comes along with the sponge your bought.

2) its harmless, becuz the fishes will ignore it, cuz they know its poisonous.

3) its graceful as nudibranchs like to "free fall" in the tank and flow along with the current a bit. Its amusing to see them stretch their body to reach another rock.

4) its a time-bomb as well. if physically hurt or died tragically, they will release toxin harmful to the surrounding waters (for a while). Fishes will be irritated. If your skimmer or water flow is low, and the toxin stays around for too long, your tank might crash.

[arcanehacker]

not really that toxic lah.. I had 2 last time for for 2ft.. both died without any effects.. and I'm only using some cheapo viaaqua skimmer..

but must say.. its a very hard creature to keep.. they feed on only fresh live sponges. If they sense that the sponge is dead, they will not eat it. If you seen then crawling around you tank instead of on the sponge, you know its time to dispose off that sponge.

They love blue sponges.. but create a mess when feeding on it..