Worm looking things....

[Stacey1990]

Hi, I'm not sure if I'm posting in the right place so apologies if not. I was hoping someone could help me identify what these worm looking things that are in my tank.
So two day ago I decided I would restart an old tank I had in the house. Everything in the tank, except for the heater, has never been used before.
I've just came in from work to find these worm looking things in the corners of the aquarium. Does anyone have any ideas as to what they are? TIA

 

[WhistlingBadger]

Probably some sort of detritus worms, though I've never had ones so dark colored before. Probably harmless.