Tiberium wildlife

Tiberium's mutagenic traits often resulted in irregular mutation when a living, unshielded organism came into contact with it's fields. The results of these mutations could vary, the victim could've been changed into a horrible Visceroid, an irregular, uncontrollable mutated organism or it could evolve, eventually turning into a Tiberium Fiend. Tiberium Floaters were also a propably outcome of mutatuion.

Visceroids
Results of uncontrolled, irregular Tiberium mutation, these organisms are essentially a large, unstable body mass, constantly changing it's shape never reaching a stable state. Parts of the original victim may be recognized within the Visceroid, but no way exists to bring the mutated one back.

Visceroids are extremely resilient when fought in tiberium fields, their simple structure without any internal organs allows it to quickly rebuild itself. Adult forms were extremely hostile and aggressive.

During the Second Tiberium War, Nod's chemical missiles, carrying processed Tiberium waste, released Tiberium-based gas upon impact, which had enhanced mutagenic capabilities.

Baby Visceroid
Although decently resiliant, especially against infantry, baby visceroids were incapable of attack. They basically wandered the Tiberium fields and patches until they found another baby visceroid, at which point they would transform into an adult visceroid.

Adult Visceroid


Adult Visceroids were very capable of attack, however. When two baby visceroids joined together, the demeanor or personality of the Visceroid changed. Not only was the adult visceroid more resiliant and still able to heal in Tiberium, but it was capable of swallowing a non-cyborg infantry unit in one hit. It was also effective against vehicles, more than a match for a single Titan Walker. Further, its speed allowed it to retreat to a Tiberium Field when it was damaged.

Tiberium Fiend
The scientific name for this creature is 'Canus Tiberius' due to it looking similar to a very large dog, almost the size of a small elephant.

Fiends have Tiberium crystals embedded in and running down their back. The Fiend attacks by launching a peculiar projectile, which may very well be a shard from the Tiberium crystals grown on it's back. The shard dealt extreme damage to infantry and light vehicles and could damage even the more resilient heavy combat ordnance.

Floater


Floaters began to grow more and more prevalent as time went on, and the first phase of the Second Tiberium War drew to a close. Floaters hovered over the battlefield, releasing clouds of Tiberium Gas behind them, which made them very effective against infantry - they could potentially turn infantry into baby visceroids with the gas it released. Furthermore, the floaters' electric attack, which it could use when in contact with the target, was extremely effective against both vehicles and structures. The floater could even stop the vehicle it was attacking from firing.

General Non-Specific Usage
The first recorded 'usage' of Tiberium Creatures was by the forgotten. As they attempted to rescue their leader Tratos, they saved a Tiberium Fiend from some Nod soldiers - in gratitude, the creature assisted them in rescuing Tratos, but eventually threw itself against the Nod defenses and was destroyed.

The second usage was of a pack of Tiberium Fiends. As a last ditch measure, the main mutant base containing what Cabal believed to be the Tacitus unleashed a number of Tiberium Fiends, but they were cut down by the powerful Nod forces present in the area.

Finally, Cabal managed to control Tiberium Creatures, by having drugged civilians lure them out from the Genesis Pit. From there, the creatures would attack anything they saw, including GDI forces. Cabal used Tiberium creatures at least twice: First was to destroy a GDI outpost and numerous civilians from the area immediately surrounding the Genesis Pit. The second use was in his attack on a similar outpost - but far larger enemy forces and civilians were present in the area, so the attack was a failure.

Counters
Firstly, Tiberium creatures were very vulnerable to railguns and other high powered weapons such as the Cyborg Commando's plasma weapon. These powerful weapons could destroy all Tiberium Creatures in a single hit. Furthermore, anti-tank weapons were effective against all types of Tiberium Creatures; in groups of 5 or more, Titan Walkers or Tick Tanks could easily destroy Tiberium Creatures.