encircled by attached to attached to insect sclerite cuticular spur The difference between an appendage and a spur is the lack of muscles attached to the spur, otherwise, the mandible would be also a spur. Spines are multicellular evaginations that are not encircled by conjunctivae. Moveable beetle horns are spurs while not moveable beetle horns are spines. The multicellular evagination of the cuticle that corresponds to an epithelial fold, composed of some sclerite that is encricled by a conjunctiva (moveable). ring conjunctiva multicellular cuticular evagination somatic muscle somatic muscle, invertebrate