This Miraculous is being used for evil purposes — specifically, creating supervillains who attempt to steal Ladybug's and Cat Noir's Miraculouses.
When not transformed, the brooch is oval-shaped and its front is purple. It opens up like a locket, in which an image can be placed. The edges of the brooch and the back of the front part are gray metal, some of it branching out on the outer area of the front of the brooch. When Nooroo inhabits the Miraculous, it becomes a dark purple button, with four light pink strands of fabric coming out from it, making it resemble a butterfly or moth.
The Moth Miraculous grants its wielder the ability to sense positive or negative emotions in order to precisely pinpoint a targeted person's identity. The wielder can energize a butterfly, which turns it black and into an akuma, to be sent to possess an object of the person. Then, the Moth Miraculous holder is able to communicate with the person to offer him or her powers. Once they accept, they transform into super beings. In addition, the wielder can telepathically connect to the possessed person to talk with them. If the akumatized person is using their powers wrongly or not the way the holder wants them to, the holder can cause pain to the akumatized person by controlling the person's body to a certain extent or take away their powers.
In "The Collector", it is revealed that a Moth Miraculous holder can akumatize themselves; to do it, however, they need to first create an akuma and then give up the possession of their Miraculous.
However, these powers do have their limitations. Hawk Moth appears to only be able to make one akumatized villain at a time, and it seems that he must wait for some amount of time between creating villains.
Butterflies are a symbol of transformation and resurrection.
If used for good, the Moth Miraculous can create superheroes instead of supervillains.
It can also give people hope to fight when the world is in danger.
The power to cause pain to an akumatized person or remove their powers is supposed to be a safeguard to prevent the person from using their powers wrongly or evilly.
Currently, there is a photo of Mrs. Agreste inside the brooch.
In "Ladybug & Cat Noir", the inactive Miraculous is large enough to sit in its bearer's palm and contain a photo, but in "The Collector", the inactive Miraculous is notably smaller, being the same size as the active one is without wings
The Moth Miraculous is currently the only known Miraculous that is being used for evil.
Although it has yet to be seen, people can decline to become akumatized, like if they don't despair enough in Hawk Moth's case.
Master Fu mentions in "Ladybug & Cat Noir (Origins - Part 1)" that he thought the Moth Miraculous had been lost forever.
As revealed by Thomas, Season 2 will explain how Hawk Moth found the Miraculous after it was lost.