Animal regenerates from one cell

Experiments in Israel with the sea squirt Botrylloides leachi have shown the animal can regenerate its entire body even if all that's left of it is a single blood cell. This ability was known in some less complex invertebrates, such as worms, but scientists were surprised the relatively complex sea squirt could do the same. This ability is still beyond the reach of even the simplest vertebrates, but further studies may reveal how regeneration abilities diminished as vertebrates evolved.