PROBLEM TO BE SOLVED: To provide a seaweed bank capable of creating a seaweed community capable of promoting the adhesion and growth of seaweeds effective in each zone under the sea surface, especially an infralittoral zone in the early stage, raising a phytophagous animal such as an abalone, a top shell or a sea urchin from a larva or a spat, growing the phytophagous animal to a grown imago and favorably promoting the cycle of alteration of generations at a low cost, providing mother seaweeds, feeding reproductive cells to a rocky area or a concrete block group around the community without causing adhesion of seaweeds yet, extending and forming the seaweed community to the surroundings and serving also as a habitat or a spawning ground for various species of aquatic organisms in a wide sea area. SOLUTION: This seaweed community forming unit is obtained by carrying out the integral molding or integral attaching of a platy concrete member designed to enable the control of the void diameter of an optional size and disintegration rate as one to plural adhesion substrate members 1 onto the top surface or a slope of a usual concrete block 2, a usual concrete block unit formed by stacking, a frame unit made of steel by assembling steel materials into the form of a frame or a composite, etc., of the steel materials with concrete. Thereby, a seaweed community is formed or formed as a base for feeding reproductive cells of seaweeds to the surroundings.
