Queen anticorns are assigned this rarity. Owners of queens may request a new common MYO slot once a month, bound to the queen's hive.
Often the target of anticorn collectors (who are in turn rarely successful), rare ants sport some unusual traits, most of which are quite useless to the ant's survival.
Sometimes, an unusual feature may show up in a nest of anticorns. This almost never directly impacts the anticorn's survival - except where anticorn enthusiasts and collectors are concerned.
Your run-of-the-mill anticorn. They sport a wide variety of candy colours, and are mostly sweet (please don't eat the ants).