“Gumbo crabs”  are primarily used for seasoning in stock and gumbo. To me, they are an essential ingredient in Seafood Gumbo. They are hard-shell crabs with the top shell removed and the cavity with the gills cleaned out. The legs and claws are still attached. These are generally smaller crabs that would not yield good lump meat but pack all the flavor of larger crabs. They are sold frozen in seafood markets. Check out Cajungrocer.com for some (I am not an affiliate of Cajungrocer.com but I know they provide quality products and services.