With the understanding that monsters are as real any other organism, albeit in a far less fantastic manner than what would be expected, it became a dedicated endeavor to create a definitive definition for these creatures. The sheer variety of the increasingly expanding number of species made the task an ever escalating and difficult one to undertake. Conclusively, it was decided that monsters, despite sharing numerous similarities with the kingdoms Animalia, Protista, Fungi, and Monera, would be given a separate taxonomic kingdom to call their own: the kingdom of Monstra.

Of course, there then came the additional difficulty of classifying the species within this new kingdom. Once more, the diversity in biology led to much frustration and argumentation among taxonomists. Finally, it was decided to categorize monsters depending on the shared physical characteristics and abilities possessed, such as possession of the hydrocarbon organ and heat- resistant scales serving as the defining feature of Ignisan species.

Distinct stages achieved through natural growth, forming abrupt and drastic changes in the appearance and behaviour of the species, is the defining feature of monsters. It serves as a reduction of competition between juveniles and adults for food and shelter, and a method of gaining newfound strength and defensive capabilities. Each stage in a monster's life cycle occupies a different ecological niche, with certain species developing diets contrasting their previous stage.

Oviparity is the method of reproduction of the Monstra kingdom. Producing hard or soft-shelled eggs, which can number in the hundreds depending on the species, monsters lack the necessity for copulation to facilitate fertilization. It is hypothesized that this asexuality is a means of energy efficiency. Without the need for sexual intercourse, species have a surplus of energy which they can now use for other activities.