Two B's in This Striped Orb

Photo date: April 7, 2017. Photographer: Mark Mahin.

The photo below shows a mysterious orb I photographed at Grand Central Terminal in New York. Besides a strange stripe,  there are two letter B's you can see if you look closely and tilt your head a bit to the left.  One of the B's is below the center of the stripe, while another is above the center of the stripe.

This is the third time I have photographed a mysterious orb with this pattern, which I call the "two-thirds of a Y" pattern (because it looks like a Y missing its left third).  Below are two other examples of the same pattern.