Professor Alexandre Meinesz (L), director of the marine environment laboratory of the university of Nice-Sophia-Antipolis, and one of his aide, Laurent Burtaire, seen at work May 6, trying to help clean up the floor of the Mediterranean between Monaco and Cap Martin which, since 1991, is covered in more than 30,000 hectares by a weed "Caulerpa Toxifolia" which destroys marine life, leaving nothing but a barren green bottom to the sea. Researchers have recently discovered this species of leeches " Ascoglosses " which feeds from the chlorophyl in the toxifolia and may provide a solution to this particular ecological problem.