Fertile eggs are normally large white and plump. However, several variations in the outward appearance of the eggs can be seen. Most of these minor differences don’t seem to pose a threat to the survival of the egg – at least from my experience. Weird eggs often yield normal babies. Sometimes the hatchlings are smaller, especially if the egg was on the small side, but from my experience that doesn’t affect the adult size of the animal.
Sometimes eggs have “windows”. These are spots where the shell is not fully developed. The windows are not the same color as the rest of the egg; rather they are yellow spots. The shell may be thin enough to see through. From my experience, windows are among the more common of egg variations and don’t pose much of a risk.
Another variation occurs when the shape of the egg is transformed. These eggs may have a bump or cone shape at one end. This deformity is usually coupled with an odd color – similar to that of a slug. I call them “cone head” eggs. This variation seems to be more debilitating but I have hatched healthy snakes from eggs like these.
So what should you do when your snake lays a weird egg? When in doubt, incubate it. Candling can help determine if an egg is fertile or not. The only eggs I don’t incubate are slugs – when your snake drops a slug it’s pretty obvious. If the egg goes bad, remove it. What happens if the dieing/rotten egg is stuck to the clutch and I can’t remove it? I just leave them attached to the pile. Sure your incubator stinks and the egg gets moldy but the others don’t seem to be affected by it. If the whole clutch goes bad then it is usually one of two things. Error on the part of the keeper or the clutch was doomed from the start.
Remember: when in doubt, incubate it. I bet you will find ball python eggs very hardy – even the weird ones usually hatch!