Detailed analysis of particle size, morphology, elemental composition, crystalline structure, and thermal degradation behavior reveals significant differences between ratite and crocodile eggshells, showing their unique environmental adaptations and biological functions. Ratite eggshells, characterized by smaller particle sizes, present lower thermal degradation and are more suitable for applications requiring flexibility and resilience. In contrast, crocodilian eggshells have more extensive and denser particles, giving them a more uniform structure and therefore contributing to their higher thermal stability and mechanical strength. The variation in activation energy profiles between different parts of the eggshells indicates the complexity of their degradation processes. In this regard, ostrich eggshell presents more complicated, multistage thermal degradation patterns, and may be suitable for layered thermal stability applications. In contrast, the uniform degradation behavior of emu eggshells suggests its utility in systems where consistent thermal performance is essential. Similarly, the stable and predictable degradation profiles of river and swamp crocodile eggshells make them ideal candidates for environments requiring high durability and resistance to thermal cycling. This research highlights the natural design of eggshells and provides valuable guidance for the development of biomimetic materials. By mimicking the structural and thermal properties of these eggshells, it would be useful to create thermally stable and mechanical materials suitable for a wide range of industrial and biomedical applications.