Mystery eggs have ? on them and somehow the dot can turn into a creepy grin. These eggs form by Lulu using her ruby necklace that she gives to a person that seems "lost". She will then say, "Just do what y'all wanna do!" (Yataro kotobai yapare ekage!). This will hypnotize a person and corrupt their Heart's Egg. When that happens, the child will Character Transform, but they will have a ? bearing on their head and will cause chaos, along with Lulu's necklace. Amu encourages the child under control about how they were or how to fix their problems. The egg then sometimes turns into an X-Egg, which Amu purifies.