I have a worm (not a health issue!)

[motorslave]

This morning I was getting to do a little maint. in the tank and looked just in tiome to see a grey worm disapear back into the LR. Didint see much more than a flash of it. Seemed to be the diameter of cooked spagehtti. Quick little sucker too. Didnt see a head or anything, but it was grey and seemes to be almost translucent but not quite. Any ideas?

Robert