The christmas snowflake. I took this image on Christmas Eve. Very rare find to have the X design. What likely happened here was the crystal formed as a split star. That is, the arms grow on two or more layers, separated from each other by a column. In this case, it was likely a two tiered crystal where the 2 missing arms grew on the other end of the column. Split stars can grow in any combination: 5 arms one one, 1 on the other, 2/4, 3/3. In this case the arm containing the other two branches broke off somewhere in the cloud leaving behind the X. It was quite windy this day so collisions would have been frequent. A rare form, I've been doing this since 2013 and have only ever found this one. Sometimes an X can form from two crossed needles, but it is rare to find an X with the arms fleshed out, and even more rare it happened on X-Mas eve.