Help what is this???
 

I was looking at my aquarium and this long purple thing came out of my live rock! I didn't have time to take a picture but it was about and inch long, flat had small little spikeythings on it's sides and it just slid out compressed itself and when back in. It was kind of catapiller like but flat to the rock. I have bristleworms but this doesn't look anything like one!

ID PLEASE

Thanks
SeaSerpant

Could be a fireworm :/

cold very well be a bristle worm, i have one that will poke out 2-3 inches and is a greyish purpley sorta colour

Bristle worm.