Thanks for all the comments,
Yes, it is a glass in there. I need to hold up some corals temporary.
After 6 years, the frogspawns took about 1/3 of my tank.
When I moved the tank to the new location, I dropped the frogspawn and it broke up into multiple smaller pieces.
I have been trying to sell and trade them to make some rooms.
I have 5 more new sps in the last 3 months. Will post up some new pictures once I get my camera back.