Lost world in a crystal ball

I used to watch a movie when I was a kid where some kids found a crystal where there was some kind of lost word with monsters/aliens. I remember the kids were being followed and put the ball in a backpack and they were in a factory too. I imagine this movie would be around the 80s or 90s. Any ideas what the name of the movie could be?

I'd say Solarbabies 1986 or The Glitterball 1977. Most likely Solarbabies.

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You can't raise your voice when the lion gets here man.

This question sounds familiar. Search the threads here.