Tetrapod moulds are by far the most striking shape in the Betonblock® range. Tetrapods are concrete structures that protect shorelines and river banks by acting as breakwaters. Tetrapods, after the Greek word for ‘four feet’, are shaped like a tetrahedron: a triangular pyramid with four faces and four corners. The legs of the tetrapods hook into each other, creating a row of stable concrete breakwaters along the coast.