A sphere, a cube and circular plate of same material and same mass are heated to same temperature. Then cooling of

$-mc\frac{dT}{dt}=\epsilon \sigma A{T}^4$

$\frac{dT}{dt}=-\frac{\epsilon \sigma A{T}^4}{mc}\propto A$ (for same mass)

For the same mass, surface area of plate is largest and that of sphere is smallest.

So sphere cools at slowest rate and plate cools at fastest rate.