Goats.
Also octopi. But octopi aren't mammals. Right?
Goats, sheep, cattle and horses.
They are rectangular.
no
because they are square
because they are square
No, their eyes are round, however, the pupils in their eyes are rectangular.
No. They have rectangular pupils like a goat, horse, or cow would, not square.
Yes, and only a few species have rectangular eyes. Sheep, Goats, Octopuses and Toads have these rectangular shaped pupils. Typically classified as prey, these animals need to have a defense both day and night. But they don't have vertical slits due to their need to survey their surroundings more accurately. The narrower the pupil in relation to the horizon, the greater the accuracy of depth perception is in the peripheral vision of the animal. The perception of depth must be considered with these animals who spend their time evading predators in a rugged terrain. From The Evolution of The Rectangular Eye http://www.science20.com/variety_tap/evolution_rectangular_eye
Animal pupils come all different shapes and sizes. A cat has slit shaped pupils, and a chicken has round pupils. Some goats even have time glass shaped pupils. Many different shapes.
A triangle.
cuttlefish
no, only plant cells