Pirate brittlegill or Crab brittlegill

The cap is 3–8 cm across, occasionally up to 10 cm. It starts convex, soon flattens and finally becomes depressed in the centre.

The colour is violet, dark purple, lilac or wine-red, sometimes greyish pink. The centre is darker at first but soon fades to dirty pink, olive or yellowish, often with bright yellow spots. A form with an entirely yellow cap has also been described.

In wet weather the skin is slightly greasy, but it dries quickly from the margin and then looks matt and velvety, as if dusted. The skin peels easily, about a third of the way to the centre.

The cap is 5-15 cm across, hemispherical when young, becoming flat and spreading with a slightly depressed centre with age. The cap skin is matte, slightly sticky in wet weather, dry and matte in dry weather, and peels easily 2/3 of the way to the centre. It's wine-red, purple-violet, burgundy in the centre, paler toward the edge, fading to pinkish-grey and ochre. Mature caps have fine radial grooves at the edge.

The gills are cream or pale yellow at first and a rich ochre-yellow when mature. They are fairly crowded, becoming more distant with age, attached to the stem and joined by cross veins near the base.

The spore print is pale yellow to ochre. A white print points to a different russula, such as the charcoal burner or the purple brittlegill.

The gills are attached or free from the stem, moderately crowded, fleshy and brittle. They're cream-white when young, becoming ochre-yellow to yellow-brown with age as the spores mature. Spore print yellow-ochre to yellow-brown.

The stem is 3–8 cm tall and 1–2 cm thick, cylindrical or slightly club-shaped. It is pure white, rarely pinkish, and yellowish in wet weather.

Young stems are firm; old ones become chambered or hollow, especially at the base. There is no ring and no volva.

Stem 5-10 cm tall, 1.5-3 cm thick, firm, fleshy, cylindrical, hollow inside in old mushrooms. It's white when young, with a characteristic pink or wine-coloured tint, and where pressed or cut it slowly turns yellow, then brown, a diagnostic feature. Surface smooth with fine lengthwise wrinkles. No ring.

The flesh is white, yellowing with age and lilac just under the cap skin. It is brittle, as in most russulas, and does not change colour when broken. Field guides describe the taste as mild and sweetish.

Flesh firm, brittle, white; it slowly turns yellow when cut, then brownish over time (especially in the stem), a characteristic reaction of the species. The smell is distinctly fishy and briny (smoked herring, shrimp, fish) and is the main diagnostic. Taste mild, nutty, with no bitterness or acridity.

The key feature of the species: the base of the stem smells of iodoform, an old-fashioned antiseptic. The smell stays at the bottom of the stem and is not always obvious, so it is worth checking several specimens. The cap and gills have no particular smell.

Distinctly fishy and briny: smoked herring, cooked shrimp, fish. A diagnostic feature of the species, easy to notice when you cut it and still there in the finished dish.