A team of Israeli and German scientists from Ben-Gurion University of the Negev (BGU) and the Max Planck Institute of Colloids and Interfaces has found an enamel-like layer in the mandibles of freshwater crayfish, according to an article in Nature Communications titled “Enamel-like Apatite Crown Covering Amorphous Mineral in a Crayfish Mandible.”

Dr. Shmuel Bentov from BGU’s Avram and Stella Goldstein-Goren Department of Biotechnology Engineering discovered that this species of crayfish protect their teeth against wear by producing a highly mineralized protective coating based on calcium phosphate, which is strikingly similar to the enamel of vertebrates. The “enamel” in the crayfish tooth serves as a protective layer for the softer under layer that is made from amorphous calcium carbonate.
“Enamel is the best solution for coating masticatory (chewing) organs,” Bentov explains. “We assume that in the course of evolution, both vertebrates and this crayfish independently developed enamel-like tissues to address similar needs. Crustaceans discard their old teeth during the molting events several times throughout their life, and grow new exoskeletons and teeth regularly and rapidly.” 
Dr. Amir Berman, also from the Department of Biotechnology Engineering, and Professor Amir Sagi, from BGU’s Department of Life Sciences and National Institute for Biotechnology in the Negev, investigated the mandibles of the Australian freshwater crayfish cherax quadricarinatus in cooperation with Dr. Barbara Aichmayer and her colleagues from the Max Planck Institute in Potsdam, Germany. The BGU team is presently investigating the formation process of this material and its ramifications.