Omphalos: An Attempt to Untie the Geological Knot is a book by Philip Gosse, written in 1857 (two years before Darwin's On the Origin of Species), in which he argues that the fossil record is not evidence of evolution, but rather that it is an act of creation inevitably made so that the world would appear to be older than it is. The reasoning parallels the reasoning that Gosse chose to explain why Adam (who would have had no mother) had a navel: Though Adam would have had no need of a navel, God gave him one anyway to give him the appearance of having a human ancestry. Thus, the name of the book, Omphalos, which means 'navel' in Greek.

Darwin is mentioned several times within the book, but always with considerable respect. Gosse had attended meetings at the Royal Society where evolutionary theory was tested by Darwin before the publication of Origin—and had even made similar observations himself about variation of species in his own studies into marine biology—and considered Darwin's reasoning scientifically sound.