can anyone ID this for me?

The seond pic is good old aiptaisia... Yer gonna wanna get control of thoses ASAP.. If you have kalkwasser mix, make a nice white mixture of it, put that into a hypodermic (goto pharmacy, ask for diabetic needles... Answer 50 questions as to why you aren't a drug user then answer the next 100 about fish tanks.. I had to heheh) and inject each one carefully.. Taking the rock out of the water will help, just don't lose the spot where they were cuz it'll look like jelly when it's retracted..

It's not the end of the word, but getting em while you just have a few is much better than dealing with the 200 you'll have in a month..

Also, don't try to rip em, scrape or nothing.. They'll jsut grow back..

btw, cool crab! I'm anxious to hear what kind it is too... I've never gotten to look closely enough at my emerald crabs to examin the eyes, but it looks similar in other respects.. Are the legs hairy? I ask cuz when I bought emeralds the lasttime, I got a red one in the bunch... Emerald crab, you'd expect green, right? So much for logic =)

1) Probably from the family Majidae, but no way to ID further than that. Maybe harmless, maybe not...my philosophy is to pull hitchhiker crabs before they can cause any trouble.
2) Aiptasia - see Raven's post
3) The remains of a colony of tubeworms that left behind just the stony tubes. There may be a few still alive in that bunch - look for little red or white feather tufts.
4) Barnacles, mussels, or similar encrusted inverts. These likely won't last long in aquariums, but neat to watch in the meantime.

Aiptaisia are bad cuz of how fast they multiply... I had 50 in my tank in a matter of weeks... They have a potent sting should they deposit themselves near a coral, and will wipe them out quickly.. I've also read they can harm your fish, though my fish never seem to get near mine... I still have them and I kill em when I can get to em... Once you get em, you never get that laaaaaast one, so get rid of em while ya can...

btw, I asked the same question: What's so bad about em? =)

Boogie,
Majidae pretty much contains the decorator crabs such as the arrow and spider crabs. I am thinking it is one of the "reef" crabs in the Xanthidae family, probably Paraetisus sp. The hairy legs kind of give that away. The bodies on these are usually sculpted with bumps and lines but not all of them are that way.

Another solution for the aiptasia is peppermint shrimp. They took care of all but one big one during an outbreak I had.
Brian

this might be off topic, but where did you order your liverocks from? They look AWESOME

Originally posted by Reefscape
Boogie,
Majidae pretty much contains the decorator crabs such as the arrow and spider crabs.

Click to expand...

Good call, right as usual. This is what happens when they make me teach classes before 8am.