The lobster mushroom is not a single species but a host mushroom — usually a Russula or Lactarius — engulfed and transformed by the parasitic ascomycete Hypomyces lactifluorum, which coats it in a bright orange-red crust and lends it a dense, seafood-scented flesh. Prized by foragers, it cooks up firm and faintly shellfish-like, true to its name.