Marine Biologist wanted

I don't know what this is. I was breaking down my brackish water setup and I like to wait a few days to make sure there's no little fish or crabs I missed and this thing is suddenly swimming around in there.

I couldn't get a good picture so I drew one.
I live in FL and had grabbed some brackish plants from the Indian River for habitat in this tank, so it could be a hitchhiker from those, but I have not seen this creature before and don't even know where to begin researching it.

Also, if I touch it will it burrow into my skin and eat my retinas? Or should I just go release it back in the Indian River?

Before I caught it in the breeder box it was pacing the whole tank pretty quickly.

Edit: I agree this is a Polychaete (Bristle Worm) and thank you so much for pointing me in that direction. I'd like to get even more specific, but I see there are thousands of types of them and I'm unlikely to find my specific buddy. Likely it's a non-venomous detritivore and I may make a trip to the river to release him so he can keep doing his best to clean it up.