Insect and Spider Identification: CLOSED: much bigger than mosquito larvae and looks like dark shrimp, 1 by Elphaba

Elphaba wrote:
I forgot about a pot in the garden that needed holes drilled in it. I'm embarrassed to say that it was full of water and breeding mosquitoes. I went to dump it out and discovered these guys. They are about a half inch long and maybe a quarter inch wide and look like dark shrimp. They have a fin on their tail like a shrimp or a lobster. I saved five of them before dumping everything out. I'll probably dump them in one of my ponds. If I dump them in the koi pond, they'll be eaten for sure. If I dump them in the dragonfly larvae pond, maybe they'll live, so let me know what you know, so I can decide their fate!

This guy looks like he's out of the water but he's actually at the bottom of this big jar.