Twonkie

Twonkies are a non-humanoid species of life form hailing from the comet known as Twonkus 3. They appear in Jimmy Neutron: Boy Genius.

Attack of the Twonkies
After school, Jimmy made preparations to travel to the comet of Twonkus 3. As a result, Jimmy headed for the comet that arrived in Earth's orbit. After returning with samples of the comet, he discovers that a small creature that stowed away aboard his ship. Reluctant about the owning of alien pets, Jimmy gives one to Carl Wheezer and then soon everyone has them. It's then that they are exposed to good music that these little things evolve and become very violent. Jimmy then seeks a way to stop them and finds that Sheen Estevez's Twonkie has not evolved. This is because of his obnoxious singing voice that got him rejected from the chorus. It is then that Jimmy finds the more evolved Gromps and Stompers are building a rocket to escape from Earth and return home. They also encounter the final form of the Twonkie that Jimmy encountered on Twonkus 3.

Despite them leaving, it is later discovered that not all of the Twonkies have escaped and some remain on Earth.

Physiology
Twonkies are non-humanoid and relatively harmless in their more devolved state. They normally remain adorable so long as they remain unexposed to good music. If ever exposed to good music, Twonkies evolve into more hostile evolutions. Despite them being one species, they have different variations and each individual Twonkie is evolved in a different way.

Abilities

 *  Superhuman Durability  Twonkies are known to be very tough, even in their more devolved form of being. This durability makes them able to withstand a variety of different attacks. This makes them almost indestructible. They are even durable enough to withstand a variety of different energy rays and blasts.
 *  Superhuman Strength:  Although the less evolved form of Twonkie is not strong, the more evolved form such as Gromps and Stompers are known to have the ability to lift heavy objects over their heads.
 *  Adaptive Camouflage:  Twonkies are also known to have the ability to change their colors to make themselves almost invisible to the naked eye.
 *  Mechanical Engineering: 

Weaknesses

 *  Anti-Music:  Although virtually unstoppable and indestructible, Twonkies usually evolve from good music. If ever exposed to someone with a terrible singing voice, Twonkies will start to devolve and turn into their most devolved state. Exposed to even a recording of anti-music causes them to devolve.
 *  Non-Intelligence: 

Reproduction
Twonkies reproduce asexually, usually the offspring exit the oral passage of the parent. Gromps and Stompers cannot due this, only the Twonkies in their most devolved form allow them to reproduce. Baby Twonkies grow within a timespan of 24 hours and produce a new generation of Twonkies. An adult Twonkie is capable of producing a litter of 30 Twonkies at a time.

Evolutionary Stages
As an evolutionary-based species, Twonkies have a maximum of 4 stages of evolution they undergo via exposure to good music.

Twonkie
Twonkies are described as small and ball-like in their less advanced stage of evolution. These are normally adorable and liked by many, however are the only ones able to reproduce.

Stompers
If ever exposed to good music, the small and adorable Twonkie will start coughing and develop black eyes. They then turn into the second stage of their evolution known as the Stompers. These things are known to be hostile when encountered and despite their size, are very strong.

Gromps
Stompers who are exposed to music for prolonged periods of time, evolve even further into the more destructive third evolutionary stage known as Gromps. Gromps are described as more monsterous than their less evolved counterparts and are strong enough to lift and throw tables at doors.

Adult Twonkies
The final stage in Twonkie evolution are the adults They are the biggest of all the evolutionary stages and the most menacing. They are usually created when a whole group of Twonkies are trapped and exposed to music. Once this occurs, the adult will take shape and then start causing untold mayhem. They are described as to also have 3 rows of teeth for both the lower and upper jaws and 2 larger teeth on the bottom, bigger than the rest.