Spawn a broad, undulated ribbon laid in a spiral attached to substrate by one edge. With age, colour may change white to yellow and spiral becomes looser. Ova arranged in ribbon randomly; not in discernible lines.
Left: out of water,Dorset, England, September 2011.© M.W.Storey
Right: submerged, Orkney, September 2015. © A. Bignall.