1. Natural growth and formation: During the growth of Laiyang pear, the unevenness of cell division and tissue expansion will gradually form a circular bulge at the bottom. This is a natural phenomenon, which is related to Laiyang pear varieties, environmental conditions and other factors.

2. False flower pinch: In order to adjust the fruit load and promote the fruit development, farmers or gardeners will pinch off the receptacle with a knife when Laiyang pear begins to bear fruit. This operation left a scar, which gradually expanded in the subsequent growth process and finally formed a circular bulge at the bottom.

3. Natural abrasion: When the bottom of Laiyang pear is rubbed by trees, hit by wind, rain and other objects, it will be subjected to a certain degree of abrasion and external force. Over time, natural wear causes the cortex to thicken and produce convex rings.