steller's sea cow: extinct large sirenian mammal formerly found near the Asiatic coast of the Bering Sea
sea cow: any of two families of large herbivorous aquatic mammals with paddle-shaped tails and flipper-like forelimbs and no hind limbs
header: a framing member crossing and supporting the ends of joists, studs, or rafters so as to transfer their weight to parallel joists, studs, or rafters