{HEAD ~ A cell} of the outer peripheral side honeycomb unit in {TAIL ~ contact} with the outermost peripheral cell wall thereof has a corner part having a curved surface, where the corner part is on the side contacting the outermost peripheral cell wall 
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{ HEAD ~ A cell } of the outer peripheral side honeycomb unit in { TAIL ~ contact } with the outermost peripheral cell wall thereof has a corner part having a curved surface , where the corner part is on the side contacting the outermost peripheral cell wall
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH