The famous nocturnal Hex hatch of the Midwest (and a few other lucky locations) stirs to the surface mythically large brown trout that only touch streamers for the rest of the year.
Sclerite: An individual sclerite is a single, uninterrupted, hard plate of chitinous material, such as those that form the exoskeletons of arthropods. Structures are said to be sclerotized or sclerous if they are fully or partially covered by sclerites.
These other words reference the same concept: sclerites, sclerotized, sclerous, sclerotic.