Need some advice on a new project lamp that I am going to call the "crystal ball"

[Autumn]

I got this "bio sphere" from a coworker today. It looks like it could be an awesome lava lamp but I have a problem. The bottom of the lamp is cemented on with some type of material that looks like grout. I am thinking about taking a dremel and a cutting wheel to it to open it up. But I cannot think of how to reseal the cap. It has to be able to take the heat and pressure from the lava expanding. This ball has so much potential but I need to find the proper way to seal it. The entire globe ans cap are both glass. Does anyone have any suggestions?

EDIT

The dremel could not open it and now I got a small chip missing from the base which isnt a big deal. I am now soaking the sealed part in hydrochloric acid over night so hopefully when I wake up tomorrow the glue will be soft enough to scrape away.

I also found out who makes these things.

http://www.eco-sphere.com/

Turns out the one I got cost the guy over $200...I better not break this thing.

[Autumn]

How much did that globe cost you? I still cant find a way to open mine and I am starting to think it may be impossible.

[Autumn]

Where did you get it? For $40 I may buy one if I cant get this one open.

[Autumn]

Can you take a picture of how you sealed the bottom?