On the shores of a Scottish loch lie geologic deposits dating back a billion years, and within the rocks is evidence of the earliest known non-marine multicellular organism, according to a study published in Current Biology.

“We have found a primitive spherical organism made up of an arrangement of two distinct cell types, the first step towards a complex multicellular structure,” said Charles Wellman, a paleobiologist at the University of Sheffield, in a university press release, adding that it’s “something which has never been described before in the fossil record.”.

In order for life to make the monumental shift from simple unicellular organisms to complex multicellular ones, “organisms had to evolve a genome that controlled the nature of cell division and how cells stick together and how they differentiate and segregate tissues,” said Paul Strother, a paleobiologist at Boston College and lead author of the new study, in a phone call.

Earlier discoveries have confirmed the existence of such ancient multicellular life in oceans, some dating back over two billion years; it now seems possible that more than one evolutionary pathway led to the first multicellular lifeforms.