Recursim

RecurSim is a portmanteau of Recursive and Simplex.

From Wikipedia:

A simplex is a generalization of the notion of a triangle or tetrahedron to arbitrary dimensions.

A recursive simplex or a fractal simplex is a structure that’s constructed by copies of smaller versions of itself. Examples include the Sierpinski triangle:

The recursim, Sierpinski tetrahedron or Tetrix which has a very interesting fact about its dimension.

Here’s a Numberphile video if you want to dig more on this topic:

For the nitpickers out there, a “recursive simplex” is not strictly a simplex but it’s rather a hollowed out simplex and a fractal object but we take liberty in the terminology.