That's it! Thank you, Margret. According to the description it is a "square pyramidal" concrete tower. The USCG photo looks black and white but Bernd Claussen's picture captures the true colors. It was built in 1986. I spotted it when I was looking through the pictures on the link that Dave posted. It looked like it could be a lighthouse so that prompted me to start searching for a light with those markings. It's pretty unusual.