Was it a fly? Was it a cicada? Was it a bee? Was it a hummingbird? People will often notice things fly by their peripheral vision and assume that they are from this world. That is not always the correct assumption. Magical creatures are known to camouflage themselves and their things while distracting observers with something that seems obviously magical. Don't be distracted!
(It is a treasure chest of magical items for those who find it - especially kids!)