A guinea-pig-like mammal’s prehistoric urine may be one of the best tools for understanding climate change in arid regions, scientists announced Tuesday. Already, analysis of crystallized rock hyrax pee appears to contradict some results of current climate models.

Looking like a rodent but more closely related to elephants and manatees, the roughly rabbit-size rock hyrax has, for tens of thousands of years, lived in colonies of up to about 50 individuals in sub-Saharan Africa and the Middle East.

The animals use communal “toilets” called middens, where rock hyrax waste slowly crystallizes into a layered, amber-esque, smelly substance.

Like amber, the middens can contain valuable evidence—in this case, traces of how much grass the animals were eating and isotopes indicating how dry that grass was.

Read the rest at nationalgeographic.com