A close look at ice on a window pane revealed these barb-like crystal growths. They appear very three dimensional from the way the crystal faces interact with the incident light.
These small ice crystal columns are comprised of half-hexagons which became larger with each successive crystal deposition. This image has been digitally resampled to twice the capture resolution.
Low temperatures and humid air in still conditions, allowed the formation of these columnar crystals on vegetation emerging from the surface of a frozen flooded field. Romanno Bridge in the Scottish Borders.
On this frozen flooded field, various ice crystal formations had formed, some comprising crystals whose edges were picked out by further smaller ice crystals.