Marrow (Sarah Rushman) is a superheroine appearing in American comic books published by Marvel Comics. The character is commonly depicted in association with the X-Men. She is depicted as a mutant whose bones grow out of her skin. These can be removed from her body, providing her with potential knives, clubs, and body armor. As a child, Marrow was taken in by the Morlocks, a band of grotesque-looking mutants who hid in tunnels beneath New York City. As a young adult, she formed the violent splinter cell Gene Nation until, under the orders of Morlock leader Callisto, she joined the X-Men to redeem herself. She made progress controlling her powers and learning a moral code, but eventually fell in with the paramilitary group Weapon X. Marrow first appeared in Cable #15 (Sept. 1994) and was created by writer Jeph Loeb and artist David Brewer. However, The Uncanny X-Men writer Scott Lobdell and artist Joe Madureira defined her powers and temperament. She later appeared as Marrow in X-Men Prime (1995).