
"[It's] huge for a single cell. If I had cells that big I'd be six kilometres tall and weigh three trillion kilograms," said Sönke Johnsen, a biologist at Duke University in North Carolina, and the expedition's chief scientist.
Single-celled animals, known as protists, are usually the size of a pin-head or much smaller, but the size of this "sea-grape" isn't the most unusual thing about it.
"We watched the video over and over," said Johnsen. "We argued about it forever… [we thought] these things can't possibly be moving. There are other large protists, but none of them move."
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Slow roll
The tracks left by them, as they feed on sediment in the Bahamas, are up to 50 cm long, and it's estimated that they roll at a rate of just 2.5 cm a day. See a video slide show of the animals here.
The researchers said that it's possible that the sea grape may be a descendent of the creature that made the tracks that are well known from the fossil record. Or – like the tuatara or the coelacanth – the protist could be a living fossil, that has changed little for as many as 1.8 billion years.
"This description of similar [sea floor tracks] made by the giant single-celled amoeba is very important," commented Jim Gehling, a palaeontologist at the South Australian Museum in Adelaide. "It shows that we can never rely on one piece of evidence to demonstrate the origins of motile animals."
I think that is pretty cool. A single cell that big is amazing. Plus the trail of poop is pretty funny

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