I found a duck egg on 4-26 in a depression intentionally made behind my peony in front of my garage. It’s a good secluded spot. 6 years ago I had a mallard lay 11 eggs and successfully hatch all behind my tree near this spot. This is the time of year here they hatch. This year she never returned. Just 1 egg. Yesterday I shined a light on it. There is definitely something inside taking up most of the egg interior. I cannot see veining. Today I did the dunk test. I have no knowledge about this, just what I’m finding online. It stayed on the bottom and never floated up. I cannot imagine this egg is good with no incubation. It has significant weight to it, and the shell is intact. Can I do anything to get a successful hatch?