Lithothamnium, or maërl, is a calcareous algae living in the seabed off the Glénan Islands (Finistère). Its exceptional richness in calcium, magnesium and its very numerous trace elements: silica, iron, manganese, zinc, nickel, boron, molybdenum, make it a remarkable remineralizer. Fast-acting basic mineral amendment (Calcium oxide: 43% - Magnesium oxide: 5%) NFU 44001