worm ID? (no pic)

[dan-in-den]

under a red lens, it appears to be brownish in color and about 2 - 3cm long. It's diameter is about 1 - 1.5cm.
If I had to describe it, it looked like one of those "rolly polly" or "pill" bugs that curl into a ball when disturbed. It appeared to have multiple legs like a pill bug. Another description would be that it looks like a little finger cut off at the first joint.
It was in an open sand area between rocks and as soon as the light hit it, it high tailed it behind/under a rock. I'm guessing that it only took a second or two to cover a distance of 3 or 4 inches.
I've looked a lot of pictures of peanut worms but nothing looked close (except the closed up ones) and from what I've read of peanut worms, they don't 'run'.
The shape is similar to a mantis shrimp but I haven't heard any clicking sounds or lost any livestock.
I'm going to try and do a flash picture and try catching him in the open again.
Any ideas?

 

[bang guy]

See if it resembles any of these critters:

 

[dan-in-den]

The coloration was like pic #1 but I didn't see any appendages other than what looked like swimming feet underneath (kinda like a shrimps)
The shape was like pic #2 but I didn't notice any eyes.
Definitely nothing like #3
I assume, that if it's #2, you want him?

 

[bang guy]

Most of the Cirolanid Isopods (#2) are detritus or carion consumers. Let's hope that's what you have

 

[dan-in-den]

Here's an excellent article by Dr. Shimek about cirolanids:
Cirolanids
This picture was in the article and the coloring looks right. I wish I would have had more of an opportunity to observe it, especially to see if it had those unique eyes.
It's got me scared now
I haven't lost anything yet so I'm really hoping that it is of the scavenger variety and not the parasitic type. Of course, it could be a pregnant female and is just waiting to give birth to 30 or 40 hungry offspring before getting hungry again.

 

[dan-in-den]

okay, think I got the pic size right this time:

 

[bang guy]

Definately Cirolanid. If you don't see any marks on your bottom dwelling fish then you're probably OK.

 

[dan-in-den]

I'm doing a head count and physical on all livestock every morning now
I've kinda rearranged some of the rocks so that I have a clear view of where he went under. If I want to try and trap him, would I use the same tactics as trying to trap a bristleworm?
This Saturday I get my first set of lighting (72" 4x96 PC w/moonlight). The moonlight will be sitting right over his rock.
I'm assuming that the nocturnal creatures won't be bothered by the moonlight? (yes I know that sounds stupid but I had to ask )