They look like they might be detritus worms, but it’s hard to tell. Detritus worms have a tube shape. If you see little feelers (or branches) coming off of one end of them, you probably have Hydra instead. If they look flat and have a triangular head, you have Planaria.
MeatPotential6989 
They look like they might be detritus worms, but it’s hard to tell. Detritus worms have a tube shape. If you see little feelers (or branches) coming off of one end of them, you probably have Hydra instead. If they look flat and have a triangular head, you have Planaria.
Could you zoom in a bit more? Might be hydra if its attached to the glass or detritus worms if floating.