The Boom Box is a temporary resource building and decoration introduced in the Cosmic Rock Medal Event for Clash of Clans, available to players with Town Hall 6 or above. It was available on the standard rewards track when you reached 16,000 Res Cosmic Shards. It also was the central hub for the event, producing Cosmic Shards (up to 100 per day) which are used to earn Rock Medals for rewards.