When someone says something is “egg-shaped” you don’t usually imagine that it’s perfectly round. You also might not imagine someone would pay more than $700 for a remarkably spherical egg.

Apparently Kim Broughton, owner of a hen — since renamed Ping Pong, for obvious reasons — that produced a perfectly spherical egg on Feb. 17, never imagined it either. The British 44-year-old told the BBC she was about to crack the egg open to use in her pancake batter when a friend told her not to. The spherical egg, born to a Buff Orpington hen, a breed that has been called the “Scarlett Johansson of the chicken world,” was, the friend said, “one in a billion.” So Broughton decided to offer the egg up for auction on eBay, where it fetched £480, which works out to about $731. Nope, not chicken feed!

"When it was at £20 I thought, 'Who'd pay that for an egg?'" Broughton told the BBC. "And then it went through the roof."

Broughton, who plans to donate the funds raised to a cystic fibrosis foundation in honor of a friend’s son, says she’s keeping an eye out for more round eggs, in hopes of raising more money for the charity. In the meantime, she’ll ship the egg to the buyer in a “hard box,” so there’s no danger of it cracking.

Because if that $731 egg arrives in bad shape, someone’s going to have to scramble for an explanation.