Taking it out would probably be smart
I actually just pierced myself with my little buddy maurice (foot long or longer bristleworm) in my sump. All i new was i grabbed something squishy so i jerked my hand out of there.
Lucky i knew i had gotten jabbed by a bristleworm otherwise i would've thought i had gotten hit by an underwater cacti
!
Just soak it in vinegar thats what i did and they went away in a few minutes... Little did i know that i had left the vinegar in a clear cup on the table and i tried drinking it later... not a great experience!
Hope everything gets better in your scavenge for under water "cacti worms"
SeaSerpant