Hitch-hikers on LR - What are they?

[x Mouse x]

I put the first lot of LR in my tank about 4 days ago, and this morning I awoke to find a few new inhabitants that obviously hitch-hiked home on my rock.
Being a complete novice I have no idea what these are (or if they are detrimental to my tank!), so I was hoping someone with a bit more knowledge than me might be able to identify them.

http://members.iinet.net.au/~moonlight/mouse/inhaba15.jpg

http://members.iinet.net.au/~moonlight/mouse/inhabb30.jpg

http://members.iinet.net.au/~moonlight/mouse/inhabd25.jpg

There is also a couple of crabs, but I can't get a clear pic of them.

Thanks for your help

Lisa

[Telco Guy]

The first appears to be some sort of nudibranch. The other two are pistol shrimps. Pistol Shrimps are generally good inhabitants. They use the enlarged claw to make a popping sound that they use to stun their prey (copepods and other small critters). The nudibranch is another story. They usually do not do well in newer tanks and may not survive. :(

So, where did you get your LR? Tell us some more about your tank.

[x Mouse x]

Thanks Nick :)

I got my LR locally (store called Veba's). My tank is a 52G with a sump. I've got crushed coral sand substrate, and in the process of getting the LR. Since it's so new, the only inhabitants came with the LR. Currently going through the cycle process, so it will be a little while before I'm able to stock it.

The nudibranch is really great to watch, so hopefully he will be ok if I can keep the ammonia levels down.

Lisa

[x Mouse x]

The nudibranch is history... poor guy. I think the shrimp bit it too :(
Here I was worried about the hitch-hikers being detrimental to my tank, and it turned out the other way around! Please see the thread "help my Live Rock is turning into dead rock" for details

Thanks
Lisa