Crab brittlegill (Russula xerampelina) is a large mushroom with a wine-red cap. Older mushroom smell of shellfish or herring. This mushroom grows in grassy woodlands and peaty soil. It it common in Iceland. The species is mainly characterized by its odour and is often called 'herring russula'. The crab brittlegill is the main species. Abroad it seems to prefer coniferous woodlands but in Iceland it is often found in birch woods with the leaves of the mountain avens flower (Dryas octopetala). All young herring russulas are edible but the flesh becomes maggoty and the odour grows stronger with age.