The closest presumed relative of the millipede is Nematozonium filum, which lives in South Africa. The common ancestor of N. filum and I. plenipes was able to spread to present-day California prior to the supercontinent of Pangaea breaking apart around 200 million years ago.
"Over millions of years, and through evolutionary time, the millipede became specially adapted to this unique area in California," Marek said. "It's known as a relict species because it is isolated both in space and evolutionary time. Because of this, and significant development (climate change, transit, housing and other human industry), the species is certainly in danger of further habitat loss and potentially extinction."
The leggy animal's habitat is also home to other unique animals and plants, which include local flowers, trees, ferns, mosses, salamanders, scorpions, beetles and trapdoor spiders. Many of them are found no place else on Earth.
Casey Richart, a San Diego State University evolutionary biologist, agrees the leggy millipede "appears to be micro-endemic and should be of conservation concern. The importance of this species is potentially very high. Since it has diverged so anciently from its nearest relative, it likely has unique chemical compounds, some of which may have utility to human society."