Leedsichthys were the biggest fish that appeared in the Jurassic period and the largest fish that ever lived. They grew to 27 meters (75-80 feet) long, and sometimes larger, making it the largest bony fish to ever live.
Leedsichthys filtered out any tiny plankton, any small animals floating in the ocean. They also lived in huge sholls. At a certain time of year, the lived on their fat reverse and that really shorted out the healthy fish from the sick ones.