Usually we worked on marine organisms like algae and invertebrates of senegalese coasts but it’s the first time we investigate sea urchin species. Specimens of the Cassis Sieberiana were collected in December 2002 at Dakar (Senegal).Fresh sea urchins were exhaustively treated with CHCl3 /MeOH 1/1 (V/V). After evaporation of solvent the oily residue (4,3616g) was passed through an RP 18 column. The CHCl3 soluble fraction has been analyzed through spectroscopic means (NMR, Electro Spray Ionization mass spectrometry). It has been shown to contain the 1 triacylglycerol A