The Number 68
68 space groups are Tetragonal.
68 is a Truncated Tetrahedral Number.
The Chemical Element Erbium has an atomic number of 68.
The Year 68 AD"Historical record has it that two Buddhist missionaries from India, on the 30th day of the 12th month, in the year 68 AD, arriving at the court of Emperor Ming of the Han Dynasty. They enjoyed imperial favours and stayed on to translate various Buddhists Texts, one of which, The Sutra in Forty-two Sections, enjoyed wide popularity."
"It is said that the first Buddhist monastery in China, or at least one of the first, was Baima Si or the ‘White Horse Temple’, near Luoyang, Henan Province, believed to have been constructed in the year 68 AD."
In the year 68 AD Nero, Roman Emperor, committed suicide.