VertigoXLR8R222

ive got a local caught crayfish when i first got him i noticed a tiny white worm right by his mouth one day it was right by his eye stalk its just attached and waves around and really doesnt do anything else and it doesnt seem to bother the cray at all now we have a problem theres like five of em and now i need to figure out how to get rid of whatever it is does anyone know of a website that i could use to find out what this thing is i dont know if its a hydra it doesnt look like the pictures of hydras that ive seen it looks like a tiny white leach thats always stretched out atleast that what i think of when i see them move they cant be more than 2 mm long any help would be great lee