Mushroom lamella (gills) are excellent examples of convergent evolution. "Convergent evolution is the independent evolution of similar features in species of different lineages. Convergent evolution creates analogous structures that have similar form or function but were not present in the last common ancestor of those groups." It was once believed that only fungi of the order Agaricales possessed lamella, but it has since been discovered that several orders of fungi developed lamella to disperse their spores separately. The structure of lamella is so incredibly efficient at maximizing surface area that it's no wonder this dynamic design arose independently in multiple different basidiomycetes.