Riddles,riddles,riddles

Hi guys, have you guessed the answer to the previous riddle? Well, the answer is air, because air is lighter than a feather, but no one can hold it forever. Here's the next riddle for you guys: What state is round on one side, high in the middle, and round on the other side?
P.S.- this riddle works better if you speak it

Please post your answers in the comments
Bye:)!