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These galls are intresting (imo) thinking of a biomimicry approach for the Intelligent & Guerilla Beehive design:
Some herbivorous insects create their own micro-habitats by forming usually highly distinctive plant structures called galls, made up of plant tissue but controlled by the insect. Galls act as both the habitat, and food sources for the maker of the gall. The interior of a marble gall, formed from the bud, is composed of edible and other structural tissues.
Oak galls have been used in the production of ink since at least the time of the Roman Empire. From the Middle Ages to the early twentieth century, iron gall ink was the main medium used for writing in the western world.