The presence and involvement of proteoglycans in crustacean biomineralizations had already been
suggested [26,27]. Very recently, immunodetection of proteoglycans has been performed on histological sections of Cherax quadricarinatus stomach showing that four studied glycosaminoglycans (dermatan sulfate, keratan sulfate and chondroitin-4- and 6-sulfate) were detected both in the gastrolith-forming epithelium and in the gastrolith organic matrix [28].