OK, so I know that this is not the most spectacular movie prop in existence, but the "Critters" movies are amongst my favourites and I've wanted a Critter egg for years now....
I finally found one at an affordable price the other day and jumped at the chance. At last, my first screen used prop from the "Critters" saga!
The egg is (I believe) solid resin.
The egg with the production used script I got it with:
Screencap from the movie:
The egg with my replica Krites (I'm working on a better display for it):