I had to pair these 2 cases as earrings because the caddisfly who made them used a piece of lapis as their bottom stone on their case.  It was amazing to find this.  When I collect the caddisfly larva, some of them are already in their natural case but may not have completed it. So I put these caddisfly larvae in a simulated stream with other types of gemstones and let them finish.  These 2 caddisfly larvae picked out lapis to finish their cases with.  Amazing!