Today's awareness of environmental pollution and the idea of creating a reuse area for waste is one of the trend topics. The base opinion, regarding the reuse of any material is that all resources are inherently limited in the world. In the ethical approach, it is a moral issue that people take responsibility for future generations to protect nature. Eggshells are one of the most used natural biomasses. And natural harmless eggshells deserve to be researched to reveal their potential. The aim of this study, blending the characterization processes with the research published until now, finding criteria for the unique structures and application capacities of eggshell species, ensures choosing the right type as biomass in the industry, and directing the eggshell usage to the appropriate applications and industries. In many industries, finding benchmarks of eggshell types in their unique structures and application capacity gives a clue to selecting the right type and directing the eggshells to a suitable place. In this study, different species of eggshell (Coturnix Coturnix Japonica, Anser Anser, Denizli Hen, Alectoris Chukar, and Struthio Camelus) were characterized by XRD, FTIR, AFM, Stereo Microscope, SEM, XRF, and TGA analysis. Calcined forms of eggshell samples were characterized by XRD, FTIR, and XRF analysis. TGA analysis results are used as a precursor to determine the temperature of calcination (800-900°). XRD results show that the CaCO peak is 2Ɵ=29.58° for all eggshells. The reason why this peak is not observed after the calcination process is that the entire CaCO structure is converted to CaO. In FTIR results, the C-O stretching band which is observed at 1424 cm is the main characteristic band of selected eggshell species. When AFM images are examined, it is seen that the surface of small eggshells is rougher, while the surface of the eggshell becomes smoother as the egg size increases. SEM and stereo microscope images show that the shell thickness increases as the egg size increases.