Glass refers to the front "glass" of the tank, and you will get to see the bottom of the starfish when he gets there.
I'm glad you are enjoying the aquarium so much, and that you found our forum. Don't be shy about asking questions about either the aquarium or general computer questions. ( those should go in the gaming/Hardware software forums ), we will be more than glad to help you with those as well. We have alot of computer guru's here and should be able to help with whatever you run into.
Once again Welcome to our forum and I hope you enjoy your time here.
PS. Looks like Jim answered while I was typing.