This is totally cool.
After collecting the [caddis fly] larvae from their normal environments, he relocates them to his studio where he gently removes their own natural cases and then places them in aquaria that he fills with alternative materials from which they can begin to recreate their protective sheaths. He began with only gold spangles but has since also added the kinds of semi-precious and precious stones (including turquoise, opals, lapis lazuli and coral, as well as pearls, rubies, sapphires, and diamonds) seen here. The insects do not always incorporate all the available materials into their case designs, and certain larvae, Duprat notes, seem to have better facility with some materials than with others. Additionally, cases built by one insect and then discarded when it evolves into its fly state are sometimes recovered by other larvae, who may repurpose it by adding to or altering its size and form.