Poriferans, better known as sponges, are squishy, stationary and filled with holes. Ctenophores, also called comb jellies, are soft blobs wreathed by feathery cilia.

For the past decade, the two groups have been caught up in a raging battle, at least in the pages of scientific journals. At stake is a noble place in evolutionary history: closest living analogue of the first-ever animal. A new analysis, published Wednesday in Royal Society Open Science, hands victory back to the sponges , although more bouts are sure to come.

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All animals, from sponges and comb jellies to humans and other mammals, have particular characteristics in common: We’re multicellular, our cells have nuclei and we consume food rather than make it. We also all have a common ancestor, which inhabited the oceans at least 550 million years ago and shared those traits. But no one knows for sure what that first animal looked like, or how it lived.

That’s why scientists look at existing species to shed light on the founder of the animal kingdom.

“By comparing modern animals, we’re trying to infer what the ancestor was like,” said Antonis Rokas, an evolutionary biologist at Vanderbilt University. “How complex was it? What kind of genes did it have, and what kinds of traits?”