It's called the Desert Megaphone. It's in the middle of no where. South of Mojave Road. You have to hike up to it. Nobody knows how it got there or why. Rumor has it that there is a dude that puts skins over each end and plays it like a drum.
I am sure Dennis Casebier at the Goffs schoolhouse and museum (Mohave Desert Heritage and Cultural Association) would know
great pics, BTW, I think I recognize one of the mines