It’s easy to get excited about new fossil discoveries, but sometimes a second look at an old find can reveal something just as surprising.
Ctenophores, also known as the "comb jellies", are an ancient phyla of animals. They have no HOX genes, at least some of which are present in every other animal except themselves and sponges. They lack many of the basic immune system adaptations common to all other animals, including sponges.
The recently discovered harp sponge, Chondrocladia lyra, make not look like something you'd bring into the bathtub, but what it lacks in sponginess it more than makes up for in predatory behavior. The harp sponge uses those narrow spines to snare small fish and crustaceans, which it then digests whole.
In the evolution of organs, skin came first. The discovery that even sponges have a proto-skin shows that the separation of insides from outsides in multicellular animals was key to their evolution.
Researchers have discovered 650-to-640 million-year-old sponge fossils at Australia's Flinders Ranges. These fossils predate the oldest known animal fossils by 90 million years and antecede the blossoming of life during the Cambrian Explosion ~524 million years ago.