The evolution of fishballs began 530 million years ago during the Cambrian explosion. It was during this time that the early chordates developed the skull, leading to the first craniates and vertebrates. The first fish lineages belong to the Agnathaball, or jawless fish. Early examples include Haikouichthys. During the late Cambrian, eel-like jawless fish called the conodonts, and small mostly armoured fish known as ostracoderms, first appeared. Most jawless fishballs are now extinct; but the extant lampreys may approximate ancient pre-jawed fish.