Description:
Gametophytes: soft and fleshy, brownish-red fronds, 500 mm long, 250 mm broad, irregularly split or lobed, rarely proliferous, with a very short (2-3 mm) stipe from a minute attachment disc. Tetrasporophyte (Haematocelis-phase): thick fleshy crust; difficult to identify and rarely reported.

Habitat:
Gametophytes are found in mid-intertidal, large pools and the shallow subtidal (?? m), annual, developing in spring; south-western and western coasts north to St. Kilda and east to Dorset, uncommon; tetrasporophytic crusts are apparently exclusively found in the shallow subtidal.

Similar species:
Dilsea carnosa is much thicker, darker red, commoner, and more cartilaginous, has rounded-spathulate blades, and several blades arise from a relatively large basal disk; Halarachnion ligulatum is thin and filmy, never fleshy; Kallymenia reniformis is commoner in the subtidal generally lobed and the lobes are frequently kidney-shaped.

Key characteristics:
Fleshy frond, lack of lobing and, generally, marginal proliferations; in herbarium specimens the fertile fronds feel like fine sandpaper to the the touch.

(In: Seaweed Site - ©Michael D. Guiry - http://seaweed.ucg.ie/descriptions/Schdub.html)