Duck Laid an Egg?

We have a pool and last Friday a male and female decided to visit. We found an egg on Saturday on our cement. They continue to come back every morning for a dip and then they sit in the sun for about an hour. Then we do not see them until the next morning, other than the female coming in for a few minutes 1 evening. I had to move the egg about 20 feet for safety. They still go by the egg and have moved it a few times maybe a foot or so. What is everyone thoughts?