Ears

These colonists have ears that are rounded and seem to stick out at the sides, like dumbo rats.

These colonists have no exterior ears, only holes similar to lizards that are usually covered by fur on species that have fur.

A colonist can have up to two extra ears on either side of their head. When paired with another ear mutation, you may pick and choose whether all extra ears or only some have the other ear mutation.
This may be an entire duplication of the ear or just partial, such as an extra ear tip.

These colonists have longer ears than average and they can seem to tilt ever so slightly along them. They are usually the same width as normal - think rabbit versus fennec fox.