Eggs with their own cooking timers

Those crack British egg scientists have devised a method to label each egg with invisible ink that changes color when the egg is boiled to the desired consistency. You need to buy a full set of soft-boil or hard-boil eggs, though.

Why not just do a little cross-marketing or coupon deal with the makers of those egg timer doohickies, instead?

(from the Boing Boing)