Cholzhauer,
It may actually have a mailbox associated it with if you don't find it under Extension ID. Sometimes this is done so they can Recall the Hunt Group to the Voice Mail application and then they don't have to create a special Call Routing Announcement that does a Time Out to another mailbox. Since the Notification of a Hunt Group mailbox is set to None, by default, then it can be used to light the Message button of any phone to alert them there are messages for the Hunt Group.
Voice Processor > Devices > Mailboxes > {HG extension}
Thanks,
TE