Well folks, I think this is a huge bird egg, maybe some kind of Pterodactyl. There are little bones you can see inside but the whole egg seems to be very porous. The long line is an umbilical cord that has been stretched to make it concave. It is also heavy and big, 8.5″ x 7″ x 2″ The head has a realllly long beak forming.
Forming on the back are parts that should be forming inside the egg.
It is shown here with some other eggs which might be birds and the little brown bird!