PROBLEM TO BE SOLVED: To allow filling of as many shells as possible and to furthermore allow the filling of the shells without a gap even while a water-permeable case that is a constituent element of an artificial fish reef or an artificial seaweed bed is easy in working and can be produced at a low cost.SOLUTION: A water-permeable case 1 which is a container having water-permeable faces in a part or the whole and is filled with shells thereinside comprises: a case body 2 having side faces 21 each at least set as a water-permeable face and having a bottom face 22 closing one of open ends surrounded with the side faces 21； and a lid body 3 removably closing an opening part 23 that is the other of the open ends of the case body 2. The case body 2 has a sectional polygonal shape in which a crossing angle between the adjacent side faces 21 and 21 is larger than 90 degrees.【課題】人工魚礁又は人工藻場の構成要素である通水性ケースにおいて、加工が容易かつ安価にできながら、できるだけ多くの貝殻を充填でき、しかも隙間なく貝殻を充填できるようにする。【解決手段】一部又は全部に通水面を有する容器で、内部に貝殻を充填する通水性ケース１において、少なくとも側面21を通水面とし、前記側面21に囲まれた開放端の一方を底面22で塞いだケース本体２と、前記ケース本体２の開放端の他方である開口部23を着脱自在に塞ぐ蓋体３とから構成され、ケース本体２は、隣り合う側面21,21の交差角度が90度より大きな断面多角形としたことを特徴とする。【選択図】図１
