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whatsthis12-550x458Here’s something on my path toward dragonflies on the bogs and along the lakes of Saskatchewan, Canada. Name it and win $5 off any of my outings or lectures. And if the summer monsoons have driven you indoors with time to kill, consult the complete lineup in the What’s This? challenge. (Collect the whole set!)

Added July 6: Well, this one was easy. Everyone got it. What the heck have you all be doing in Michigan?

Yeah, it’s a fossilized coral that went by the name of Hexagonaria percarinata. It now resides in rock formations dating back to the Devonian about 350 million years ago (an important period in dragonfly evolution, by the way). But why so round and smooth? Easy: glaciers and waves. Glacial ice sheets plucked chunks of the fossilized reef, ground some of their rough edges, and left them to the waves of Lake Michigan, which have a way of smoothing out many things. We find these gems around Petoskey and Charlevoix, Michigan. It looks as if Patti Haynes was first to name it as fossilized coral and Kathleen Moore put its “type location” on the title. Both winners. It’s nice to see a few Michiganders in the mix of replies. Sara Backer wins her customary honorable mention (for wackiness, er, I mean creativity).

That particular stone pictured above has been with me on journeys for decades. I’m not one for ritual, but that pebble makes me feel safe (which is why it rides with me on my motorcycle). There’s power in rock. By the way, I’m in Thunder Bay on Lake Superior, and below is where I’m heading (with my canoe, camera, and insect nets), which means you won’t hear from me for a while. Damn, many miles to go — but many bogs and prairies on the way.


  1. ruth says:

    this…………is MY new lucky stone?

  2. Paula Gills says:

    It’s a Petoskey stone. Gills

  3. Patricia Clay says:

    It looks like a Petosky Stone but I don’t think they are found in that area

  4. Elise Polli says:

    Petoskey Stone.

  5. Mary crane says:

    It’s a petoskey stone from Lake Michigan. We used to collect them when I was kid and went there for a week in the summer. It’s really some fossilized Coral but I don’t know what kind.

  6. Judy Brook says:

    Oh, wow! That is a Petosky stone! It is fossilized coral. I remember finding them when I was a grade schooler visiting northern Michigan.

  7. Ellen R. Dettwiler says:

    Fossil coral often called Petosky Stone — also found on beaches of Lake Michigan in Lower MI.

  8. John Snell says:

    When I visit my old digs in Michigan, we call these Petoskey Stones! I hope all is well and safe travels with great adventures!

  9. Susan Sawyer says:

    When I was a kid, I picked one of these up in the gravel along the tracks in Iowa (M&StL, the Minneapolis and St. Louis, which crosses the Rock Island Line in Grinnell). Somebody else gets the first guess…I carried it with me for years. So beautiful, this pattern!

  10. Tim Newcomb says:

    Petosky stone…I have a bunch of these I collected from Torch Lake in northern Michigan.

  11. earthmom2013 says:

    This is a Petoskey stone.

  12. c. willoughby says:

    Michigan state rock, the Petoskey stone! – C. Willoughby

  13. Michele Claeys says:

    It’s a fossilized organism now called a petosky stone…makes me think of many pleasant summer days spent hunting for them on Lake Michigan.

  14. Jennifer says:

    Easy, a petoskey. Tons of them at the top of the mitten.

  15. Sara Backer says:

    This is why you shouldn’t take your parachute club near a volcano.

  16. Diane says:

    Petoskey stone! Brings back memories!

  17. Linda Wurm says:

    coral fossil?

  18. vermonter says:

    is it a *really* old sponge?

  19. Kathleen Moore says:

    It’s a Petoskey stone. I looked — in vain — for them at Higgins Lake in Michigan.

  20. Leda Beth Gray says:

    Looks like fossil coral.

  21. Patti Haynes says:

    OK, I’ll give this one a try: it is an ancient fossil (is that redundant?) from a coral reef.

  22. Kim Sargeant says:

    It resembles a Petosky stone, but less uniform than I have seen…and I don’t think you would have found one that far north and west. So, fossilized coral?

  23. Chris Graff says:

    A Petoskey stone from Michigan

  24. Andy Mills says:

    It’s a rock. A fossil rock.

  25. Gayle Hanson says:

    Petoskey Stone…fossilized coral.

  26. Sue Cloutier says:

    Perhaps this is a coral from the Burgess Shales of Canada that has been moved by the erosive forces of water to a riverside where you plucked it from the stream rounded rocks to tease us with another impossible “What is it?” and, please, keep them coming!

  27. Emily says:

    A Petoskey stone. Happy travels.

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