Ibexes

Look closely at the walls of this Dam.

Look closely at the walls of this Dam.
Driessens & Verstappen, Fulgurites Endoscopy (2001)
A fulgurite is a tubelike formation in sand or rock, caused by lightning. The immense heat in the core of the beam makes the sand vaporize, and a beautifully glazed inner surface remains. A machine is developed to observe these inner structures of fulgurites. The objects, mounted on an XY table can be viewed through an endoscope.
Harm Van Den Dorpel, Ostrich