The ancient synagogue in Matera is a cave carved deep into the limestone. Over the course of time, cyanobacteria have grown in the cave due to the special climate and the special way light enters the cave. The green color of
the rock walls caused by the bacteria thus provides information about light
and time. In the mirror installation Solar Plexus, the light from the cave is directed by a double reflection onto a place that never came into contact
with light and therefore remained free of cyanobacterial growth.

While one mirror captures the sunlight, the other mirror redirects the light and reflects it onto the cave wall. This redirection of light causes cyanobacterial life to develop in this spot previously untouched by light, eventually leaving a green, circular trace on the rock face.