Send us your shells, sand or pebbles, and we'll take care of getting them back to sea. Not only are shells beautiful to admire, they play an important role in the preservation of the marine ecosystem and the survival of shellfish. Even if the shells are empty, crumbled or broken, they continue to be essential and preserve the beach on which they are located and prevent erosion, the fragments go to enrich the sand, reinforcing it and fixing it. The shell is a rigid, hard biological structure that protects and supports the soft-bodied, skeletal animals, i.e. molluscs, contained in it. The shell is composed of inorganic material such as calcium carbonate (CaCO3) or calcium phosphate (Ca3(PO4)2) which the animals extract from seawater and secretes. All of this comes under the protection of the marine ecosystem.