Scientists detailed a truly unique sea creature that does not resemble any marine animal alive or dead.
According to Live Science, Tribrachidium had three limbs, all of which were mirror images of one another. Like a starfish has fivefold symmetry, this organism had threefold symmetry, a feature not seen in anything alive today.
The researchers detailed Tribrachidium in a study published in the journal Science Advances.
"For many years, scientists have assumed that Earth's oldest complex organisms, which lived over half a billion years ago, fed in only one or two different ways," study co-author Simon Darroch, an assistant professor at Vanderbilt University, said in a press release. "Our study has shown this to be untrue, Tribrachidium and perhaps other species were capable of suspension feeding. This demonstrates that, contrary to our expectations, some of the first ecosystems were actually quite complex."
Some 550 million years ago, Tribrachidium used a feeding method known as "suspension feeding," which entailed using its limbs to grab food floating by in the water. Suspension feeding would have served it well if the researchers were correct in assessing the creature had limited mobility.
"Because we have no obvious modern comparison, that's made it really hard to work out what this organism was like when it was alive - how it moved, if it moved, how it fed, how it reproduced," study lead author Imran Rahman, a research fellow at the University of Bristol, told Live Science. "It can increase passage of sunlight through water and potentially increase oxygenation, as well."
