help, what is this?

good question? can we get a closer look?

Sorry, with my camera, that's as close as I could get... did you click on the picture? It will make it a little bigger.... I took it out of the tank, and there you see it inside of a small paper cup! You can imagine how small it is, and therefore, it is very hard to get a close up clear picture of it. Thanks

looks like a rat turd

a tiny liver?

Ha ha ha. Must have been a swiming rat turd! ha ha ha

Appears to be a Stomatella varia.

Stomatella varia is a good guess, but they usually have a shell. This didn't have a shell, and it has a blue color.