This shadowy egg seems to suck in the light around it, as if it doesn't appreciate being exposed to the sun
This egg was an unexpected gift from beneath Shadowfell Keep when the PCs defeated Kalarel. As Kalarel’s body was dragged into the portal and it closed shut, a portion of the shadow-stuff that was trying to escape whatever realm it came from was severed and took the shape of this large egg.
With some intensive study by Harkath in Dorn, he surmised it was indeed a dragon egg, regardless of what it may have been before being left behind on this plane of existence. He believes its makeup is still somewhat malleable and whatever eventually comes out will have taken on the properties of whatever the egg was exposed to the most. Of course that’s all theoretical speculation, and it may well be the end of the world in a thin shell being carried in Rolan’s backpack.