Archimedes Plutonium wrote in
:

Every specimen of life that I can think of is overwhelmingly
symmetrical, as if there is a underlying force to produce symmetry
and to compound that symmetry.


There are a whole lot of sponges, and most polyps that don't have
any sort of structural symmetry. You could argue that no plants have
pure structural symmetry, but there are many algae and liverworts
that don't have any at all.

In animals, the force that tends to produce bilateral symmetry is
the fact that if you are going to control various body parts, it is
much easier to do so if they are the same on each side. In plants,
it is just convenient that to make another leaf, you make one like
the last one, and put it on the other side, or rotated around a bit.

Sean