So I spent about an hour and a half cleaning up this old glass tea bottle for Aquarius's tank to be a little cave for him. After I got it all spiffed up and fishy safe I sank it into the depths of his watery home and left him alone to play with it and here is what I got.

The magical mysterious cave place...dun dun duuuun
At first he tried to swim through it because he could see through it and assumed it wasn't solid. Seemed legit but didn't work out. So he tried swimming under it and that proved to be futile as well. Upon further inspection he found an opening...could this be? There was a way inside?

It's bigger on the inside...TARDIS???

It's like a little club house. Oh no I got lost how do I get back out of here?

Oh I see now.
So that is his new toy, he loves it and keeps swimming in and out of the bottle.