1.5 is a Mobius strip (a one-sided loop)   The words on it are from T.S. Eliot's "Four Quarters"

What we call the beginning is often the end

And to make an end is to make a beginning.

The end is where we start from

We shall not cease from exploration

And the end of all our exploring

Will be to arrive where we started

And know the place for the first time.

— T. S. Eliot