<；P>；PROBLEM TO BE SOLVED: To grow oceanic lives on a block for reefs formed of a water-cleaning material produced by using steel slag, etc., as a core and coating the surface layer of the core with a glaze and, at the same time, to clean ocean water directly with the water-cleaning material. <；P>；SOLUTION: The steel slag is kneaded with a clay powder for ceramics, granulated and fired to form the core, a glazing is applied to the core and fired to form the water-cleaning material, and the water-cleaning material is mixed with cement to form the block for reefs. The block for reefs exposing a part of the water-cleaning material from its outer circumference is sunk to the bottom of the sea. Examples of the block for reefs include: a block wherein a part of the water-cleaning material is exposed on all outer circumferential faces； a block having a nearly cubic form, exposing a part of the water-cleaning material on a front face and a back face and making the other faces as rough faces； and a block formed by covering a concrete vessel for the reef with a lid having an exposure hole and exposing a part of the water-cleaning material held in the vessel for the reef from the exposure hole. <；P>；COPYRIGHT: (C)2010,JPO&INPIT
