Catch a baby brittle star (?)

[tlhood]

I had added a small brittle star (as identified by a few seasoned hobbyists) to my aquarium a few weeks back. A few days ago I had bought a cleaner shrimp who sat on the underside of a rock, and ended up dead a few minutes later. Thinking it might have been a dud, I purchased another (from another store). He has been in the tank for 3 days and has been awesome. Then tonight he sat on the underside of the same rock, and I noticed he couldn't move his legs. His little swimmers were fine, he was moving his antennae, but his long legs weren't working. He kind of floundered around and I ended up having to turn off my pumps so he wouldn't get flung everywhere.

Then it hit me that the rock that both sat on is where the brittle star disappeared when I put it in the tank. Is it possible that said star is able to paralyse prey? All fish, crabs, and snails are fine. Mr. Shrimp 2 has not died (it's been about 20 miutes), and he's still fluttering around, sitting in the sand in his cave. I can't turn the flow on though as it is still pushing him around.

Either way, I want the creepy star out of my tank. I removed 3 suspected pieces of rock, and have them soaking in a fresh water dip. If he isn't in these rocks, is there another way to try to coax him out, or should I take out all my LR (around 30 lbs). My goby and my firefish would hate it, but if it is the creepy star who is the culprit, I don't want to risk it killing something else.