Looks like an aquatic oligochaete annelid, genus Nais. I used to see these in some of my freshwater cultures gathered from a pond. Here's a Youtube video of a worm identified as Nais Variabilis:
A/O 10 Series Microstar
A/O 4 Series Microstar
A/O 4 Series Phasestar
A/O 4 Series Apostar
A/O Cycloptic Stereo
Several old monocular scopes in more or less decrepit but usable condition