ID Please - Are these Good or Bad?

[NaCl_H2O]

I posted a pic of one of these guys a month or so ago, I saw one now & then. Tonight I founf FIVE of these guys crawling around on the live rock. They are 1-2 inches long, about .5-1 inch wide and flat.

Can anyone try to ID, and any info on benefit or danger would be greatly appreciated!

Thanks - Steve

[NaCl_H2O]

Here is another shot

[BA]

that things is really wierd,but cool ifs its not bad..i want one!!!lol

[Tim Marvin]

Chitons, they don't hurt anything. If you don't want them catch the rascals and I'll take them.