Asymmetry
Internals aside, most life you see is quite symmetrical. Mammals, insects, fish and even plants are symmetrical. There are different types of symmetry of course; plants exhibit radial symmetry. It can also be partial: the trunk of a tree is different in symmetry than the leaves.
Single cell organisms however, are often very asymmetrical. Subtle in the Paramecium, very obvious in one of my favourites: Euplotes. The smaller the organism (or less complex), the more advantageous asymmetry becomes.
I'm not enrirely sure if the two here are Euplotes, but they are very asymmetrical.