Bug ? Id

[Snappy]

I got a couple of bug looking things in some Australian live rock. I have never seen these before, they kind of remind me of a potatoe bug but are more elongated in shape and seem to have 10 legs, the back is a couple of shades of brown. They don't seem to swim but crawl around like a bug. I caught one and qt'd it. I don't want something I'm unsure of in my system. I got it out my frag prop tank, I used a large piece of flat rock to built a shelf instead of using (algae magnet) eggcrate. Anyway I guess I should post a picture but does anybody have an idea what this creature might be and is it reef safe?