I had to ferret out Adam's (excellent) spoiler before I could understand the question --- https://cp4space.wordpress.com/2013/11/01/gospers-pyrominia-animation/ WFL On 2/26/19, Bill Gosper <billgosper@gmail.com> wrote:

pentiprisms <http://gosper.org/pentiprisms%3F.png> —rwg (Note Julian's tympanohedron in the upper left.) _______________________________________________ math-fun mailing list math-fun@mailman.xmission.com https://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun