This is an Easter egg variant of the Apparently Impossible Sphere Puzzle. It is interchangeable with the sphere parts to make a "Deviled egg" and an "...Avocado" like shape. The bevels were removed from the edges to give a smooth looking egg when assembled.
Since there are no flat surfaces to use as supports this is a little harder to align and put together when compared to the cube. Pinching the pieces together across the flat inside faces helps maintain an alignment so the pieces can be moved into place.
Notes:
Use the linked calibration system to therm...ally calibrate your filament and the parts will fit together right off the printer. https://www.thingiverse.com/thing:1037301 You can see in the picture that the calibration pieces have different values for the thermally compensated diameter and the temperature yet allow the parts to fit precisely even when printed on different printers.
Post-Printing
Cleanup and wear-in.
Any strings or blobs should be removed before fitting the pieces. Fit two parts together at a time and move them against each other so the stair stepping on the 45 degree slopes gets worn in. Makes it much easier to get back apart the first time. Over time it will become very easy to slide the pieces together yet it will remain snug.