i dont know
Rectangles are two dimensional objects- they have no thickness. Therefore you cannot "stack" them and so there will be no 3-D shape.
Cube
Hyperbola
Square
Cube
Stack.
cone
A pyramid will not roll and you cannot stack objects on top.
Ergonomics. The shape makes them easier to deploy en masse, makes them easier to stack together for storage, and takes up less space than a number of other shapes.
A cylinder
u stack 20 of them together