Dryland pill isopods: compact conglobating species of the American deserts and beyond, tolerant of aridity that would kill the humid tropical premiums, and slow-breeding in the way that shapes every isopod price.
They keep at the ventilated, dry-leaning end of the shelf: sandy substrate with retreats, calcium, occasional moisture points, patience. The full roll into a sphere is intact; the pace of everything else is desert-calibrated.
The reproduction rule prices the genus: slow breeders hold premiums for structural reasons, decaying over years rather than seasons, and the desert species breed slowly. Supply is thin collection plus specialist culture, and the genus trades to the isopod hobby's dry corner, where it fills the niche the moisture-loving majority cannot touch.