When I was a teenager my grandparents took me to the beach in south Texas. I sat on the damp sand, bored, and idly dug with my hand to see how deep I would need to dig to get water to well up in the hole. Something poked my finger, and I grabbed hold of it. It was a fossilized shark's tooth. It was black stone with two pointy bits on one end, (the root of the tooth) a kind of knobby bit at the center, and a long pointed shaft which was broken and jagged on the end.
Now, I presume it is possible that some tiny Chinese worker, a gifted artist, worked a small black piece of stone so cleverly as to make it look like an imperfect fossil of a shark's tooth. It's entirely possible that some faceless member of some secret conspiracy brought the stone to south Texas and buried it on the beach in the hopes that some random person would dig it up and think of it as evidence that the Earth is older than 6000 years.
It's possible. But a not very believable, to me.