You Stalker

Last weekend we planned to have a BBQ/Grill party but to our surprise we found that a bird had nested in our grill. There was already a nest with 5 light blue eggs. Because of that we left it alone and postponed the BBQ. It's been a few days now and I just checked the grill to see what happened to the eggs so far. Surprisingly the whole nest is gone from the grill but one egg has been left behind/fallen off into the depths of the grill. Is it safe to think that the egg is dead and can be removed now? Thanks.

The opening would be too small for a predator like a cat to get into it. My only guess is another bird may have came and ate it, the nest was relocated along with the eggs, or the birds hatched and the nest was destroyed.