i know bristleworms are good guys but i have a big one, maybe 18 inches, that is starting to scare me a little. should i remove it? how would i remove it?
If it's that big, it's very likely a fireworm. They are predators and should be removed.
Remove it any way you can. Some people use traps; I stalked mine for six months at night with a flashlight. Finally got him with some long tweezers. Be careful, they're fast and their bristles sting.