It can at times be disadvantageous for a mushroom to open up and free its spores in the usual way. If this development is aborted, a secotioid form arises, perhaps to be followed eventually by an evolutionary progression to a fully gasteroid form. This type of progression is called gasteromycetation and seems to have happened several times independently starting from various genera of "normal" mushrooms. This means that the secotioid and also the gasteroid fungi are polyphyletic. According to the paper by Thiers, in certain climates and certain seasons, it may be an advantage to remain closed, because moisture can be conserved in that way.