Please help with I.D

[janbokev]

Could someone please I.D this worm like creature I found in my tank. I need to know if it's good or bad and if it's bad how do I catch it. Sorry but the picture was taken via video camera then a snap shot of that I had to do it quick with a flick of the torch and that's the best I could get, Please help.
Thanks in advance
Janet

 

[Anonymous]

Looks like a nudibranch, could be friend or could be foe.

 

[chris&barb]

Its a chiton, harmless grazer

 

[janbokev]

Do Chiton not have scales things on? and It does appear to be quite long, do they get long and it pulls it's self back in as soon as the light from the torch hit's it.
Sorry to sound dumb.

Janet

Thank you guy's I have had look at some pic's of Chitons on the net and they do come in a soft form also. Once again Thank you for your help.