An approximately 575-million-year-old creature's stomach has the earliest indication of plants being digested.

Ediacara biota were chowing down on the bacteria and algae that covered the ocean floor millions of years before Americans began to observe Thanksgiving.

The Ediacara biota, a group of animals that date back 575 million years, are the earliest big organisms in the world. Even earlier than the Cambrian explosion, which took place between 541 and 530 million years ago and altered the trajectory of evolution for all species on Earth, they existed. The fossilized remains of these creatures, which are extinct, have been found to resemble discs or plant fronds; some extremely rare specimens are almost eight inches in diameter. They may have resembled soft-bodied aquatic animals like jellyfish based on the fossil evidence.

2018 saw the discovery of fossils of two Ediacara—Kimberella and Dickinsonia—by Australian scientists from rocks near the White Sea in a remote region of Russia. Scientists are currently attempting to determine what these extinct animals consumed as snacks.

More information about these peculiar and extraordinarily old bottom dwellers is being revealed by a new study that was just published in the journal Current Biology, including how they were able to eat and digest food. The team examined prehistoric Kimberella fossils that contained phytosterol molecules, a naturally occurring chemical compound found in plants that may have been this animal's last meal. A closer look into the molecular leftovers revealed that the Kimberella, which resembled a slug, actually had a mouth, a gut, and even digested food similarly to modern mammals do today.

"Our results indicate that the animals of the Ediacara biota, which lived on Earth before the 'Cambrian Explosion' of modern animal life, were a mixed bag of downright weirdos, like Dickinsonia, and more developed animals, like Kimberella, that already had some physiological properties similar to humans and other contemporary animals," said lead author Ilya Bobrovskiy, who is currently at GFZ-Potsdam in Germany.

Both creatures are members of the Ediacara biota family and have a structure and symmetry that are unlike anything else existing on Earth right now, though Kimberella was probably one of the most developed Ediacarans. The earliest fossils that can be seen with the naked eye are those of the Ediacara biota, which are also the ancestors of all living things today, including humans and other animals. These animals are our most evident, deepest roots, said Bobrovskiy.

The study suggests that the energy and nutrients from the algae they consumed may have been crucial for Kimberella's development. Pre-Ediacara biota fossils were almost exclusively microscopic single-celled organisms.

The group was successful in extracting and analyzing the sterol molecules present in the fossil tissue using chemical analysis. Cholesterol is significant because it is one of the characteristics that distinguishes animals from plants. It is also how researchers discovered that the Ediacara biota are among the earliest known ancestors of all living things.

It was already known by scientists that Kimberella may have had a gut because it left feeding traces by scraping algae off the sea floor. Kimberella was able to precisely understand what it was eating and how to digest it, according to the team conducting this study's analysis of the gut molecules. Kimberella was also so advanced that it was able to recognize which sterols were beneficial for it and had a specially designed gut to filter out the rest.

Jochen Brocks, a co-author from the Research School of Earth Sciences at Australian National University, said, "This was a Eureka moment for us; by using preserved chemicals in the fossils, we can now make gut contents of animals visible even if the gut has since long decayed."

However, Dickinsonia didn't have a gut, which really highlights how sophisticated Kimerella is and is what Brooks considers to be even more bizarre than Kimberella.

Say a quick "thank you" to Kimberella and the other Ediacara as you gather around the table to give thanks on Thursday; otherwise, you might not be able to stuff yourself with turkey, stuffing, and cranberry sauce.