Trilobite-looking creature

[azrien]

Several weeks ago, on one of my rocks I saw something that looked like a 3/4" long potato bug/trilobite. It was oval like a racetrack and had overlapping scutes. It was the same color as coralline, very well camouflaged with the rock. It did not move while I watched it so I assumed it to be part of the rock I've never seen before. A few hours later, it was gone.

Today, I noticed the same creature near the same location. I stuck my hand in and tried to remove it, but for the life of me I couldn't get it to budge, twitch, or even move. For everything I know it was part of the rock and it even felt like rock. A few minutes later I looked back in the tank and it was gone without a trace.

What in the world can it be? I don't even know where to start on looking for information about it. This is the best photo I have of it, it's very small, probably closer to a half inch wide but at the same time I have no idea if I'm seeing the whole thing. Again, it feels like rock and I could not pry it off the rock. Thanks again, I can't believe all these weirdies I'm finding in the tank. Every single day there is something new to explore.

By the way the tentacles at the right side are independent of this creature. Those tentacles belong to some misc. anemone. The photo was enhanced to try and show more of the creature's detail.

 

[Sk8r]

That's a chiton. Deep on the ocean floor they reach 2 feet long. Yours will be, I'm sure, a smaller species. They're neat. Wish I had one.

 

[azrien]

Interesting! Any idea if it is reef safe? I read something online that said it eats encrusting plants and animals off the rockwork. Not that I think I'll be removing it either way.

Thanks!

 

[Sk8r]

They're not real fast movers: they might be a problem in an acrylic aquarium: I don't know how strong the jaws are. The suction, i'm told, is pretty strong. But if it threatens things, it would be very happy in a sump, dark and plenty of crud.

 

[azrien]

My aquarium is glass, thankfully. I read their scrapers are coated in magnetite (true/untrue?) but there isn't really anything in there it could damage. I think it sticks to the rockword, and I read that its mowings stimulate further growth. The meager readings I did so far seem to suggest that removal would be very difficult, and if it's not broke, I'm not fixing it. It is very interesting to watch and I hope it comes out more.

Do you know of any chiton-ID sites? I'm trying to find some with no luck.