The entire specimen about 3″X6″
Notice the Detail?
Do you really know what a Hexagonaria Coral looked like when it was alive during the Devonian Age? Neither do I. You can get an idea by looking online at artist’s rendering based on what corals look like today.
The Petoskey Stones we find in our area of NW Lower Michigan are lovely; whites, grays of various shades, and sometimes a little pink, yellow, or blue mixed in. These are calcified fossils and polish to an attractive shine that enhances the coloration and pattern.
Underside
Many years ago I purchased a collection of rocks and minerals that contained one very remarkable Hexagonaria. I just put it aside and forgot I had it for about 20 years. My wife Bonnie sometimes dares to comes down to the shop and TRIES to as she says “neaten up”. She rediscovered this fossil with others back in the recesses of my storage area.
Hexagon shaped chambers with polyps’ peaking out
Close-up of Polyps. Notice the chamber wall striations.
I was amazed at the detail of the fossil. I simply cleaned the dust and cobwebs off with some Dawn soap and a toothbrush. I ground off the rough bottom so it sets straight. Imagine my surprise when my hard diamond wheels were sparking and I found that the fossil was not the normal Calcite, but very hard Quartz. Because this Petoskey was a Silica replacement fossil it remained undamaged and perfectly petrified for these millions of years. I have to suspect that this fossil was early Devonian. I have no idea where this specimen was found, but I was happy it was re-found in my barn and I could show it to you.
First off, my fossil has a yellow tinge. All the individual Polyps show high resolution and even perfect mouths. The living part of the Hexagonaria was called a polyp, and the dark spot we see in the center of the Hexagon shaped chamber was the polyp’s mouth. The animal had tenticles like most modern corals, that grabbed plankton as it drifted by then fed this food into its’ mouth.
See the tentacles?
The resolution is so good in this fossil that you can actually see some tenticles and perfect striations on the walls of the individual chambers.
I am knowledgeable about Petoskey Stones, but I am by far not a leading expert. I base my text on what I know from collecting devonian Fossils for 40 years.