http://news.bbc.co.uk/2/hi/science/nature/6518161.stm
With lengths over 11m, the giant gypsum crystals found in Mexico's Cueva de los Cristales are a great natural wonder.
Now, a Spanish-Mexican team thinks it can explain how these marvels acquired their immense form.
The scientists studied tiny pockets of fluid trapped in the crystals and conducted back-up lab experiments.
They report in the journal Geology that the solution from which the crystals grew must have been kept in a very narrow, stable temperature range.