Worm like organisms on the side of glass

[Neleono]

Hello,
I'm having a bit of a strange infestation of sorts in one of my tanks. There are tiny white worm-like creatures moving around on the glass of the tank. They are all close to a millimeter in length and extremely thin (some the width of a strand of hair), so very small.

This all started about a week ago. I left for a trip, and before I left, I looked over the tank very well to make sure it was all ok for a house sitter (who was caring for my pets while I was gone). Before leaving, the tank had nothing visibly wrong with it. However, after I got back, I found the strange worms. It had only been a week and now there are about a hundred of them.

In the 10g tank, I have one betta, a nerite snail, and some cherry shrimp. The tank is well planted and I have not made any additions for months. I have no idea what these things are and if they are dangerous. I am worried for the wellbeing of my tank and its inhabitance. Any help or recommendations are welcomed and any questions that might be helpful are welcomed too. Thanks!
(P.S. The worms are to small for my camera to focus on so I am so sorry I can't provide those.)

Edit: I still can't get a good picture of the worm, but my camera can focus on one that I just put under a microscope so that image is below. Hope that helps! Also after looking at this worm under a microscope it looks quite like a planarian, but it doesn't have that signature head shape and color, so I'm just not sure.

 

[coriesinhawaii]

It doesn't look like the typical planarian with the triangular shaped head. Perhaps another flatworm like rhabdocoela? Do they wiggle? Wiggling worms would probably be detritus worms. Both of those can be unsightly but are harmless to fish. They were probably hiding out in your tank in small numbers and just had a population boom while you were on vacation (maybe due to overfeeding).

 

[eatyourpeas]

I think you are looking at a Rhabdocoela. Harmless but perhaps a sign of overfeeding, and there could detritus worms as well. Decrease the amount of food and do a water change, they will go away on their own if the tank is clean.