what are these?

[SkyAurelia]

i have a second salt tank that dont have much in it, its behind on upkeep as well cause of some rl issues that recently got solved, im planing do some work on this tank to get it cleaned back up but i found these in it today can someone tell me what they are and if there good or bad please.

i do not think the thing on the glass is the same thing i have frfom the gravel in the cup, they seem to be alive and was eating things before i caught them, keeping them to the side tell i know more.

 

[Tahoe61]

Spaghetti Worm.