[code777777]

Indeed. Iron and other heavy elements sink into the core of planets as they're being formed. This leaves less iron on the surface for chemical reactions that might lead to life.

However, iron does play an important role in life as we know it, even today. Earth's molten and rotating iron and nickle core is what creates our magnetosphere that shields us--and presumably early life--from deadly solar radiation.

[sangnoir]

> However, iron does play an important role in life as we know it, even today

I would have thought the iron in mammal blood would come to mind first, but other aquatic life forms have copper-based blood, so it's not exactly required.