When this came up yesterday, at https://news.ycombinator.com/item?id=34130864 https://news.ycombinator.com/item?id=34130864 , I pointed to an article by Nancy C

When this came up yesterday, at https://news.ycombinator.com/item?id=34130864 https://news.ycombinator.com/item?id=34130864 , I pointed to an article by Nancy C. Knight, "No Two Alike?" in Bulletin of the American Meteorological Society, 1988. https://journals.ametsoc.org/downloadpdf/journals/bams/69/5/1520-0477-69_5_496.pdf https://journals.ametsoc.org/downloadpdf/journals/bams/69/5/... . > Figure 1, a photograph of actual snow crystals, not replicas, illustrates a striking example of two snow crystals which, if not identical, are certainly very much alike. ... The two very similar snowflakes are in the bottom center of figure 1, side-by-side.