The 12,000-year-old tooth was found back in December during a fishing trip and has been in a restaurant ever since.
George Church, from the Harvard Medical School, founded a company to bring the wooly mammoth back to life in 2021.
The fossilized excrement could help to shed light on what the extinct animal once ate.
The circle, named Kostenki 11, was about 40 feet in diameter with no obvious entrance.
The next decades, partly as a result of our inaction over the past ones, are crucial to mitigate climate warming. It is time to embrace innovative and proactive new experiments.
Scientists say the species survived in isolation for 7,000 years before going extinct.
The boy spotted the tooth in the grounds of a hotel owned by his relatives.
Researchers inserted the mammoth nuclei into mouse ova where they saw "signs of biological activities."
Does the foot-long fragment come from a mammoth or a mastodon?
A woolly mammoth bone washed up on the beach in Scotland.
Evidence suggests ancient humans may have hunted the mammoth and then stored the meat at the bottom of a pond.
It could be yours for about the price of a small apartment in Brooklyn.
Mammoth ivory, like modern elephant ivory, is durable and doesn't splinter easily, and so makes a good spear for hunting.