The presence of a creature as complex as "Pikaia" some 530 million years ago reinforces the controversial view that the diversification of life must have extended back well before Cambrian times – perhaps deep into the Precambrian. The discovery of "Metaspriggina", a primitive fish of similar age which seems to have already started to develop a jaw and the presence of conodonts, the teeth of an extinct type of fish belonging to the Agnatha some 20 MA before Pikaia, does provide support for that view.