The molecular coordination number (CN) changes with the surface curvature of an object in the zcluster < zdroplet < zplane < zcavity < zbulk = 12 order, while water molecules retain their tetrahedral orbital geometry despite the dangling H-O bond or lone pair at the topological edge . The effective molecular CN takes zboulk = 12 for the hcp-structured water instead of the apparent four neighbors. Thirdly, water droplet prefers the core-shelled structure with a supersolid skin. Adopted from the solid helium that displays the elastic, repulsive, and frictionless contacting motion of fragments ,