Via Wired:
... Using a technique called x-ray tomographic microscopy, researchers captured an unprecedented level of detail in the Doushanto fossils, imaging internal and external features down to a ten-thousandth of an inch. They could even see individual nuclei within the cells, some of which were caught in the act of dividing.
Interestingly, these nuclei had distinctive shapes, quite unlike the cell nuclei of animal embryos, which lose their contours when they divide. Furthermore, while the cells were rapidly dividing, they weren’t differentiating into specialized tissues. The cell clusters also sprouted peanut-shaped protrusions filled with spore-like cells.
“All of that is completely incompatible with an animal-embryo hypothesis,” said paleontologist Philip Donoghue from the University of Bristol in the U.K., a co-author on the new work, which appears Dec. 22 in Science...