Another foolishly named cage-like compound, that is a variant of adamantane. Like adamantane, it is a saturated hydrocarbon resembling fused cyclohexane rings. Not just fused in a plane (like graphite or coronene) because cyclohexane is not planar.
Rather, the fusion invoves total overlap of the carbon atoms and is more conceptual than actual. Unlike adamantane, the geometric requirements of overlapping the three axial rings with the top and bottom rings forces the three to be in boat form rather than chair. Presumably, this makes iceane slightly less stable than adamantane (due to closer approach of hydrogens).
Another way to visualise the molecule is two cyclohexanes joined into a sandwich - like cyclophane really :) The reason for the name is that ice forms this kind of structure at RTP. Obviously, you don't get stable ice structures of this size (12 water molecules!) but this is the basic 3-dimensional 'tile' that can form a whole ice crystal.