It seems a kind of transparent annelid specie. If you want you can sign up in Inaturalist. In this website you can search the common and the scientific names of this and other forms of life.

https://www.inaturalist.org/

Thanks for your answer Daniel Tecles

HI! Try compare with a  Filo Nematoda, like a Strongyloides stercoralis. If you have a picture of eggs or focus in tips.

Good look.

Thanks for your answer Francisco Kercher Berte

For me it looks like a larva of a diptera (similar to Pediciidae or Tipulidae).  Very young and thus quite transparent. You can see the tracheal system and some chitinous oral structures. 

Thanks for your answer Hubert Blatterer

There is no cilia no flagellate, so it is not protozoa, it seems as a wing of insect.