Snowflake unlikely that any two snowflakes are alike due to the estimated 10 (10 quintillion) water molecules which make up a typical snowflake, which grow at different rates and in different patterns depending on the changing temperature and humidity within the atmosphere that the snowflake falls through on its way to the ground. Snowflakes that look identical, but may vary at the molecular level, have been grown under controlled conditions. Although snowflakes are never completely symmetrical, a non-aggregated snowflake often grows so as to exhibit an approximation of six-fold radial symmetry. The symmetry gets started due to the hexagonal crystalline structure
Front and back Front and back From an articulatory perspective, phonemes can be described as front or back. Front vowels refer to vowels articulated towards the front of the mouth. This can either refer to vowels that are more front than central or, more rarely, only to fully front vowels, i.e. the ones that are articulated as far forward as possible in the mouth. A similar distinction holds for back vowels, which can refer to vowels that are more back than central or, more rarely, only to fully back vowels, i.e. the ones that are articulated as back as possible in the mouth.