I’ve never grown common guavas—this tree is in my MIL’s yard—so I don’t know if this growth pattern is normal. I don’t see it on any of the images that a quick search pulls up. Part of the flower (a sepal?) persists as the fruit grows, forming a tough ”hood”. Looking at variously-sized fruits on the tree, it seems that this hood stays the same size as the fruit enlarges. Presumably it eventually falls off. What is the purpose of this phenomenon? Is it unique to this tree?