ID please

I have no ideat what this thing is.... it moves across the glass kinda like a snail

Flatworm, yo.

so how do i kill it... there is only one right now

ive realized that in the reef world- where theres one, theres more! flatworms live on glass, rocks, and sand, so theres no telling.....

kill them only if they are harmful

im almost positive that the one in the pic is just a harmless planaria that diets on copepods and you wouldnt need to take any action unless they reach plague levels. (which they wont if you have proper water circulation)

if they do-

flatworm exit, have activated carbon prepared after dosing and you might loose a shrimp/snail or 2 that week...