dormant

Currently without human hosts. The ancient Egyptian hieroglyph
system and the Gnostic Gospels are examples of "dead" schemes which lay
dormant for millennia in hidden or untranslatable texts, waiting to
re-activate themselves by infecting modern archeologists. Some obsolete
memes never become entirely dormant, such as Phlogiston theory, which
simply mutated from a "belief" into a "quaint historical footnote."