An egg (or as Ivor Cutler wrote “a eg”). 44 × 57 mm hollow container joined by a threaded insert.
Print the outer shell with support, but make sure it doesn't touch the internal thread. Print the insert without support. Either way, cleaning support material from a thread is no fun.
Print with at least a couple of shells.
Make sure the threaded parts are fairly clean so that they will screw together easily. The thread tolerance is intentionally sloppy so it'll work with most printers.
You can glue the insert into one part of the shell if you wish.
threads.scad from http://dkprojects.net/openscad-threads/
The thread is a slightly non-standard M36 by 3 mm pitch. Standard pitch would be 4 mm which would make the container walls too thick.
Egg profile is a Persian architectural dome construction, described in Gereh & Arc by Sayed Akbar Helli, pub. Kashan (Iran) 1986, p.25.