Urofecal stones, chemically named magnesium ammonium phosphate stones, are composed primarily of magnesium ammonium phosphate hexahydrate and apatite carbonate and were originally found in bat feces. This stone type is also known as an infected stone or infectious stone because it is caused by urease-producing bacteria in the urinary tract. These bacteria include Aspergillus, Pseudomonas aeruginosa and Staphylococcus aureus, which produce urease that catalyzes the breakdown of urea into ammonia and carbon dioxide, which in turn combines with water to form ammonium hydroxide. Ammonium hydroxide is an alkaline substance that can significantly increase the pH value in urine. When the urine pH reaches 7.2, ionic ammonium can combine with magnesium and phosphate in the urine to form magnesium ammonium phosphate. During the decomposition of urea, a large amount of carbon dichloride is also produced, and carbon dioxide is further hydrated into carbonic acid before dissociating into carbonate. Similarly, in alkaline solutions, calcium and phosphate are synthesized into apatite, which then combines with carbonate to form carbonate apatite. When the urinary magnesium ammonium phosphate and carbonate apatite reach supersaturation levels, crystals are precipitated. However, these crystals must adhere to the urinary epithelium before they can continue to grow into stones. The ammonia from bacterial decomposition has an affinity for the charge of the mucopolysaccharide sulfate that protects the urinary epithelium, which changes the hydrophilicity of the mucopolysaccharide sulfate, which in turn attracts ammonium ions to the sulfate root of the mucopolysaccharide sulfate and subsequently promotes the adhesion of magnesium ammonium phosphate crystals to the urinary epithelium. Depending on this lithogenic crystal adhesion mechanism and the supersaturation of the associated ions, stones can form and grow rapidly. In vitro experiments have found that A. amoebae can produce stones in as little as four hours. Clinically, these stones can often grow into larger antler-shaped stones due to their rapid growth and susceptibility to shaping by the intrarenal collecting system. It is also specifically noted here that antler-shaped stones are not synonymous with infected stones. The latest domestic study showed that antler-shaped stones were mainly mixed stones, including calcium oxalate monohydrate, calcium oxalate dihydrate, magnesium ammonium phosphate hexahydrate, apatite carbonate, uric acid, cystine. 51% of the patients had guano stones, 78% of the patients had urinary tract infections, and 64.7% of the patients had positive urine/stone bacterial cultures, so antler-shaped stones were closely related to urinary tract infections. All magnesium ammonium phosphate stones are secondary to recurrent urinary tract infections and abnormal urinary tract anatomy, with peak age of onset above 60 years, and are more common in women. In clinical practice, care should be taken to conceptually distinguish such infected stones from stones complicated by infection. The former is an infection causing stones; whereas the latter is a stone causing an infection, which is usually due to Escherichia coli, a bacterium that does not produce urease.