Beside Nohoch Mul was Temple X (10) and Stela XX (20).  Stela XX is fascinating.  Supposedly the back side (which I forgot to photograph) contains the oldest recorded date in the Mayan world, around 16 billion years ago.  The front side is the standard ruler stepping on the captives for the gods nonsense.  I felt this stela was cool; it attracted me.

According to COBA: History, Art And Monuments, MonClem Ediciones, 2007, ISBN 9-789709-019445, pages 40-41, Stela XX also contains the most recent date inscribed on any stela at Coba: November 30, 780 A.D.  For reasons unknown, the Maya stopped carving stela at Coba after this date.  Stela XX was very well preserved because it fell over on its face, thereby protecting the front of the stela from the rain.