Even for a single birds, the MaranS has an "S" on the end - it is named from the place in France (Marans) where it comes from.
Wikipedia
Marans is also famous as the home of the Marans chicken. Marans chickens are famous as the layers of the darkest shell color of all chickens. This breed was originally developed in Southwest France between the 12th to the 14th century. The present form of this chicken was refined during the 19th century in the village of Marans. While fairly common in France, this breed is rare in America. Marans chickens lay exceptional eating gourmet eggs that are highly prized by chefs around the world.
I like how the Wikipedia tries to claim their eggs are different than any other chicken. Someone make the stupidity stop.