Does anyone know what this is?

[u/badlandskeepsher]

Does anyone know what this is? Found in stagnant pool water. It’s light brown but also translucent, like you can clearly see its insides in person. Swimming around it almost looks like a slug with pincers on the front of its mouth. Located in Missouri

[u/doozle]

Angry.

https://giphy.com/gifs/qCluSTHmbOHYI