Both of those pics are bristle worms (all are polychaete), remember, there are thousands of polychaete worms that are harmless and the ones pictured above fall into that category.That could be a fireworm, it has the bristles that remind of a fireworm, but they usually have some pretty intense colors. They almost show a bright red (and even blue color) under LED lights.
Heres a photo of one I had a while back, they are incredibly rare now a days.
Fireworms have bristles that look almost like tiny little fiberglass hairs, and there is TONS of them.
Note the bristles in the pic above vs these (a harmless bristle) these almost look singular, where the fire worm has much more fine "hairy" bristles.
(second photo is not mine)
The one in the top picture was incredibly painful for me, other bristleworms don't feel like much of anything, thats why I identified the top pic as a fireworm. Felt like a lionfish sting.
Still most likely a bristle worm. I’ve handled thousands of pounds of live rock and had my fair share of encounters with both and have had different reactions. Not all bristle worms are the same, some are just like fiberglass, others pack a little extra punch, but still a bristle worm. Also, like with bee stings, most people won’t have a reaction, but others are allergic or more sensitive to the bristles. I’m not trying to minimize your encounter, but the reality is fireworms are pretty rare these days and the likelihood of a hobbyist finding one in their tank is really uncommon.
This was also several yrs ago with rock from the ocean. You are good, I've been around here a while and love bristle worms, have had some that have been with me for 20+ yrs. Fire or bristle, this one had to go. Most just feel like fiberglass to me and I don't even notice them anymore.
Yup, those are fireworms indeed.
