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 (regional map).

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. (Related: "Spider's Blood Found in Amber May Hold Prehistoric Secrets.")

As a result, some middens are essentially unbroken, 28,000-year-old records of changes in regional vegetation, said study leader Brian Chase