Résumé : A novel sterol, strongylosterol, has been isolated from the sponge Strongylophora durissima. It has been demonstrated to be 3β‐hydroxy‐24°‐ethyl‐27‐methylcholesta‐5, 25(26)‐diene (1). Copyright © 1978 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim