Roisin’s Clamshell Shell by Leslee-Langlands | Jul 2, 2015 | patterns, Roisin, Tops Clamshell. A new design and pattern from Roisin (with contributions by Brenda)..a knitted Art piece inspired by ocean lapping on the sand at Savary Island. Knit with cotton blend, and big needles. Great for summer wear. I think it would be lovely for summer wedding wear.