I hold the bird that sings no more, Yet warriors clash behind my door. Prizefighters test their might, In my squared ring, day or night. What am I?

It's piling up, it's on the chair, oh my gosh, I no longer wear underwear. Commando I go, though clothes are there.

Used to contemplate or have fun. My parties are known worldwide. While my waving is constant, some stop to see a world in a piece of me.

Filled with precipitation, And not to boast, The most diverse biome. Finer roast.

Like Rodin's 'The Thinker,' Perched on a pot, When lost in deep thought, I'm the best spot to squat