Used as a biomarker in medical diagnostics, particularly in urine analysis to detect kidney stone formation. Its presence indicates metabolic imbalances such as hyperoxaluria or hypercalciuria. In research, it serves as a model compound for studying crystal growth and inhibition in biological systems. Also utilized in environmental studies to assess plant degradation, as it commonly forms in decaying plant material. In analytical chemistry, it is employed in gravimetric determination of calcium by precipitation and weighing. Additionally, some plants produce calcium oxalate crystals as a defense mechanism against herbivores, causing irritation in the mouth and digestive system.