A "hunger stone" exposed by the low level of water in the Elbe river is seen in Decin, Czech Republic, on Thursday. The low level of water caused by the recent drought has exposed the stones on the river bed.

For hundreds of years, these boulders have warned about the consequence of devastating droughts — and documented them for posterity. One says “if you see me, weep.”

(Image credit: Petr David Josek/AP)