Yellow excrescences resemble yellow papillae on mantle of Trivia arctica.
1: fragile, white ear-shape shell; never exposed on live Lamellaria.
2: mantle halves fused so never retract to expose shell.
3: inhalent siphon.
4: head and tentacles have form similar to Trivia.

Body length 15.5 mm. Menai Strait, Wales. March 2011.