It looks like it is built inside a giant clam, in which you can watch shows, sometimes a symphony and (possibly) plays.
The first time it appeared, It was daytime and Squidward handed the manager of the symphony his original piece. Added by VastscatmanDuring the performance of it, SpongeBob andPatrick appeared and did everything Squidward did. And the end of Squidward's symphony, the crowd cheered for him. The Conductor conducts it.