In September I retired and as a present I received from you a great art object in stained glass.

This was a particular instance of a turtle figure of a morphic sequence, as will be described in this talk.

The main message is that a program consisting of only a few lines may create a wide variety of figures, some of which having amazing patterns. In 2016 my paper on this topic appeared in the journal Fractals. Recently I extended this work to a book in Dutch for a wider audience. This book just appeared, and the title is ‘Spelen met oneindigheid, verrassende figuren en patronen’, see https://www.win.tue.nl/~hzantema/aank.pdf

In the talk some basic theory will be shown, in particular leading to the stained glass object.