Command available at terminal prompt, but nowhere to be found

view story

http://stackoverflow.com – This is puzzling. I can use the module command at the terminal prompt, but I can't find where the executable is located in the file system! I did the three following searchs: 1- which module returns "no module in ...", 2- searched module under the bin/ directories of the PATH variable ... nothing, 3- locate module | grep -e "/module$" ...nothing. None of these searches gave me the location! Suggestions, please? (HowTos)