The new body plans allowed animals to organize themselves into new ecosys- tems the Earth had never seen before. The earliest animals appear to have lived like sponges do today—trapping microbes or organic matter from the water as they remained anchored to the seafloor. But then animals evolved with guts and nervous systems, able to swim through the water or burrow into the muck. With their guts, they could swallow larger microbes, and, eventually, could even start to attack other animals. shows a 550-million-year-old fossil Cloud- ina bearing the oldest known wounds from the attack of a predator. Charles Marshall, a biologist at Harvard University, has proposed.
