I'm here playing a game of "I know what it is, but what exactly is it?" I'm losing. 
Discussion
well that looks like a woman's legs underneath it so i have no idea
theoretically looks like some kind of very large cannon round
Measure the diameter of the projectile and convert to mm, that'll help you narrow down what it is.
Thank you! I already have a lead off of that... anti-aircraft cannon maybe(?) I'll keep looking.