A lingering controversy exists in ichthyology over the validity of the four species Beebe described based on visual descriptions only, which he had observed during his Bathysphere dives. The naming of a new species ordinarily requires obtaining and analyzing a type specimen, something which was obviously impossible from inside the Bathysphere. Some of Beebe's critics claimed that these fish were illusions resulting from condensation on the Bathysphere's window, or even that Beebe willfully made them up, although the latter would have been strongly at odds with Beebe's reputation as an honest and rigorous scientist. While many of Beebe's observations from the Bathysphere have since been confirmed by advances in undersea photography, it is unclear whether others fit the description of any known sea animal. One possibility is that although these animals indeed exist, so much remains to be discovered about life in the deep ocean that these animals have yet to be seen by anyone other than him.