Order-7 tetrahedral honeycomb
In the geometry of hyperbolic 3-space, the order-7 tetrahedral honeycomb is a regular space-filling tessellation (or honeycomb) with Schläfli symbol {3,3,7}. It has seven tetrahedra {3,3} around each edge.
Source: Wikipedia — Order-7 tetrahedral honeycomb (CC BY-SA 4.0)