PROBLEM TO BE SOLVED: To provide a structure capable of securely holding a vegetation base material made from additional soil and seeds, etc. when the structure is used as a pressure receiving structure, and capable of securing implantation and breeding/culture of coral larva and marine algae when the structure is used for breeding/culturing coral and marine algae.SOLUTION: A board body 2 is composed of a grid-like structure made of FRP including vertical ribs 2a and lateral ribs 2b with numerous rectangular openings 3 formed in the vertical and lateral directions. Silica sand 4 containing a resin adhesive is blown and fixed to all the surfaces excluding the lower surface of the board body 2, which means the upper surface and four surrounding side surfaces of the board body, and four surfaces forming each opening 3 in such a way as indicated in Fig.2, to make the surfaces coarse mesh.
