If this is true, could the same be true for Mars?
Thomas Gold stated in one of his papers (which are, alas, no longer online at Cornell, but, uh, I’m sure copies exist somewhere) that hydrocarbons were not known from the Viking data (at that time the only surface probes on Mars) but that subsurface exploration through coring might find some. Time will tell (assuming Zero is voted out, or better yet, impeached).