One of my favorite shape words is torus which is a doughnut-shaped solid. Based on the examples of dolabrate and lemniscate, I'll wager the adjective is toruscate. [Homer]Mmmmm...torus[/Homer]

EDIT: Seems the preferred adjective is toroidal, toroid being an alternate noun for the same shape. Thanks to our Chicagoland correspondent, Mr. K, for that info.