...the title of this post is what I would think while holding this egg. The largest egg ever laid by anything that we can determine is up for auction in the UK.
Apparently it was some kind of giant bird in Madagascar that went extinct some centuries ago. Sidebar - have you noticed how the weirdest animals always seem to come from Madagascar? Must be something in the water*.
Anyway, take a look. If Easter eggs were this big, they'd be easier to find. ...yeah yeah, make your own punchline!
*Madagascar's biodiversity actually lends itself to its unique size and location, separate from the African continent but otherwise rich in the right biological resources for a unique and diverse ecosystem.