Thanks so much, everyone! Gaston, yeah, it does look a little dangerous, doesn't it? But that way the klickys can see the beautiful coral reef through the glass bottom.
About the dolphins... they have a little hole in the bottom of them, just like the marlins and rays, that fits into the bigger sized pegs in the coral pieces. Except the one on the far right, which is presumably older and doesn't have a hole... it has a slit farther back towards the tail joint, and I have two prongs from the coral jammed into it holding it up. Btw, the smaller tips on the coral, and the tips of the sea grasses fit holes on the bottoms of the smaller fish and the eels and hold them up.