What is this thing? Found in a brackish water ghost shrimp tank.

[BisScottie Non-Ya]

So I found this growing in a brackish water ghost shrimp tank at work and we're completely stumped. Also it secrets a white milky gunk when touched underwater. Any help is appreciated.

[Jeltz]

Looks like a lacewing larva

[Bill Calvert]

Could be a caddis fly larva. They are a close relative of moths, and a favorite food of trout and other stream fish, especially the adult flies. They form a protective shell out of silk and debris from their environment (like rocks, sticks, stems, silt, etc.) and sometimes secrete silk in self defense. They mainly eat detritus and mulm so they shouldn't be a threat to your fish.