Bone brooch

The Bone Brooch was the winning item in the Guaranteed Content poll on the RuneScape website for the 2010 Hallowe'en event. It also appeared as an option in the Guaranteed Content poll of Halloween 2007; however, it lost to the Grim reaper hood. The Brooch will, as stated by the poll description, transform the player into a pile of bones. The specifics of how this item will work are currently unknown but is likely it will work the same way as the other two transmogrification items.

Here is a quote from Jagex released about the future halloween event.

"You can also expect a monster mash this Halloween, as Pumpkin Pete brings a bit of rock 'n' roll to Grim Reaper's mansion! Our third planned update for this month will require you to be the roadie for Grim's favourite band and get the entertainment back on track. Expect to be dancing with spiders, drinking with backing singers and gathering autographs. Party-goers with killer dance moves will unlock the player-morphing 'bone brooch', as voted for by you earlier in the year."

Halloween 2010
The Bone Brooch was released to players on the 18/10/10, upon the completion of the halloween event. It allows the player to morph into a pile of bones.