caddisfly larvae from what I can find. Feeds on algae and plants. The matured fly looks kinda pretty in some specimens. There's close to 400 different kinds in existence from what I gather.
"After spending six to 10 months in the larval stage, caddisflies form cocoons. Once transformed into a pupa, the insect cuts its way out of the case;if it built one;and makes its way to the surface of the water, where it breaks out of its pupal exoskeleton and emerges as a winged adult."