This monument is situated just opposite Sudanlage 6, which housed world famous lineage of Institute of Plant Nutrition which was once headed by Professor Dr  Justus von Liebig, in Giessen, Germany, subsequnelty Professors  of great eminence  The University was given his name.
Professor Dr  Wilhelm Conrad Rontgen (1845-1923) was Professor of Physics at the the University of Giessen ( now Justus von Liebig Universitat Giessen, Germany named after Justus von Liebig)
I always saw this monument from our  lab or to be more precise lab of Professor Dr Karl-Hermann Neumann ,  (where I had a chance to work as Alexander von Humboldt Fellow)  as it was across the road. 
It dipicts some metal rods piercing the stones. Ideas of some people help advancement of mankind in forward directions and make history.