I find paperweights useful while working, and all the more so if they are appropriate in some way. Here is part of my collection.
On the left is a marble cuboctahedron. Since the edges of this shape form a symmetric graph (all 24 edges are equivalent), it made a nice example while I was working on my 2004 paper “Network Robustness and Graph Topology.” For example, the cuboctahedron is one of the Cayley graphs for the alternating group A4.
The frog on the right, on the other hand, feels right at home with some current work I’m doing on amphibian species distribution modelling.