Sea Urchin Parasite?

[Snow_Phoenix]

I was feeding my red tuxedo sea urchin an algae wafer today when I noticed a small pink worm akin to a bristleworm crawling amidst the urchin's spines. The worm was approximately 1cm long, dark pink and looked exactly like a bristleworm (besides its lurid coloring).

 

Considering that my urchin hasn't been looking his best - a few of his spines fell off even though my parameters are good and my water quality is good as well (except for the detritus mishap in my other thread), I'm just wondering if this mystery worm is some sort of parasite that feeds off my urchin's shorter blue spines?

 

Sorry about the lack of pictures - we have four cameras at home, and none of it is functioning at the moment (one has a cracked SD card, another has crappy focusing, the third is missing, and the fourth has run out of battery charge - don't even get me started on how lousy my phone's camera is).

 

Back on topic, this worm retreated into my urchin's spine-forest before I could remove it with a pair of tweezers. Either it's a commensal or a parasite - either way, anyone has any thoughts/experience on this? Can't seem to find anything on google about it.