It can be difficult to identify worm species from one picture, but that looks like a common bristle worm to me. I have dozens of them, some are up to 4 inches long and never bother anything. It is possible that it's a dangerous species, but I doubt it.
Unless you actually see it acting threatening, I'd ignore it. Panic helps no one.
Bristle worms do not kill everything they touch. There is a lot of misinformation about them. When they get very large they can become predacious, but they're fairly harmless most of the time. Just don't touch them because the bristles can hurt.