These calcified creatures were found like this by a lakeside in Tanzania.
The lake near the Ol Doinyo volcano has a natron content of 90%, a pH value between 9 and 10.5 (equal to household soap) and a temperature of 60° C. The fish that live here are adapted to extreme alcaline conditions.
It is not known what caused these creatures to die. Photographer Nick Brandt, who found them and took these fascinating pictures, supposed that they might have been confused by the highly reflective surface of the lake and flewn into it, just like birds fly into glass panes.
The water from the lake then calcified their bodies.
The pictures and information were taken from an article in a German newspaper.