Cambrian Conophyton Stromatolites from Down Under

Description: The stromatolite shown here has a conical growth habit, hence the form genus name Conophyton. It has been cut and polished perpendicular to the growing plane and thus beautifully exhibits the multiply- colored growth rings. These were thought to have grown in a deeper subtidal environment than some of the more familiar pillow shaped structures arising in shallower water much nearer the surface.

This stromatolite dates to the Middle to Lower Cambrian when stromatolite was no longer prevalent and abundant. By the Cambrian, photosynthetic bacteria responsible for the biogenic formation of stromatolite structures no longer had the earth to themselves. The oxygenated atmosphere had become toxic to some bacteria, and they had to compete with other organisms, some of which would have been predaceous to this most ancient of life forms.