These are glossosomatids, Jason. They are probably Glossosoma nigrior, though it is possible that we are looking at mixed species. The ones to the right with their aggregate of similar sized grains are classic Glossosoma, while the ones to the left with the large anchor pebbles could possibly be Agapetus. Regardless, they're all commonly referred to as saddle case makers.
In this picture: Caddisfly Family Glossosomatidae (Saddle-case Makers).
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