Simple Virii are the most common type. They are a corrupted version of Darwinians. They attack anything in range, but are fortunately very weak and can be killed by a laser shot.
Centipedes are a mutation of the Virii. They are stronger than the original Virii and have a sense of survival. When attacked, each piece will become a separate entity. Centipedes can use Souls to recreate parts of their bodies.
Soul Destroyers are a more advanced mutation of the Virii and are capable of flight. When one of these advanced Centipedes destroys a Soul, that Soul is lost for good.
Triffids are plant-like creatures that launch eggs every few minutes. Eggs burst open to create virii and other evil creatures. Triffids are stationary and defenseless at close range.
Bugs are cattle-like creatures that were hunted by the Darwinians in the early years.
Spiders are a mutation of the Bugs. Spiders use their strong hind legs to pounce on their victims. Spiders are not vulnerable to laser blasts and can only be destroyed with explosives.
Spore Generators are an even more advanced mutation of the Bugs mentioned above. They are able to lay large numbers of eggs that can birth swarms of Virii if they are fertilized with a Soul. Spore Generators can hover above ground and seed entire regions of Darwinia. The eggs are fragile so the Spore Generator has to come close to ground to distribute them. This brings the Spore Generator putting within weapons range.
Army Ants are also mutated Bugs. Individually they can be dealt with easily, but in groups they are quite dangerous. Army Ants will carry Souls back to their nest to be replicated into more Ants. Army Ants will attack anything that approaches their nest.