Coral

Here are several pictures showing a cast of a boring clam outlined in a Tampa Bay coral head. The clam looks like limestone and the coral is agatized. The second image may actually show the outer shell.

Nice Tampa Bay specimen Victor. I never seen or found a coral with the clam preserved in it. That is a unique specimen.

I rarely find clam borings in any corals except those in south Georgia. The Florida corals don't seem to have them. However I have not collected at Tampa Bay since it is picked over so much. But there are almost no limestone/calcium carbonate fossils in the Withlacoochee River in south Georgia. It must be about chemistry. Lots of boreholes though.

Then again the south Georgia silicified corals are large and can be silicified 100% even if they are up to 3 feet in diameter. Not like that in many other places. I found large corals in Florida but the centers are not silicified. Conditions for silicification must be very favorable in the Withlacoochee.

No doubt that is a boring clam hole. It is dead round.

The coral in Tampa Bay-Santa Fe-Zephyrhills-Aucilla-Withlacoochee-Suwannee-Black Bay-Swift Creek-Plant City and several other locations is all quite different in how it silicified. From Tampa Bay north to Valdosta is almost 200 miles and there is a lot of geologic variation in that area. Some locations have unusual color. Some small or large. Some pseudomorph like Tampa Bay and the Withlacoochee.

Since coral is elevation dependant it can be found in many places in it's range. I'm not sure other collectors know that. But you can drive down I-75 and stop at most creek crossings at 75 to 90 feet above sea level and find silicified coral. Or drive down primitive clay roads at that elevation and find coral heads. Sometimes I see large piles of them on a farmer's property where he cleared his field of them.

And Giant clams help coral reefs.

sharkresearch.rsmas.miami.edu/the-understanding-of-giant-clams-contributions-to-coral-reef-health-continues-to-grow/

"Finally, giant clams make their shells out of calcium carbonate, the same material hard corals use for their skeletons, so their shell material can be incorporated into the reef framework.

Giant clams benefit coral reefs in many ways, and their presence is indicative of reef health. Unfortunately, overfishing has put giant clams under great pressure, and their local extinction could be detrimental to coral reefs."

Boring clams don't limit themselves to boring thru coral. They are not particular.
Compressed hard bottom gets the ream too.



This batch of various silicified death plates had many borings. To be tumbled.
These silicified sediments typically form a layer 1 to 6 inches thick in a single vien running long distances.
They are under the coral.
I don't know the timing of their silicification relative to the coral's silicification.



Guessing there is a large percentage of bryozoans in this sediment.
Much of coastal plain chert is composed of piled up and compressed bryozoans.



Lots of dead critters. Maybe these clams that met their demise are borers...bryozoans are mixed with the clams



Then there are many strange silicifications. This appears to be a cast of some sort. Color likely from sitting in an ancient black muck mire. How old can muck deposits be ?

Somehow sponges can bore holes. These are silicified oysters found with fossil coral. Never found a coral with sponge borings.






Upland creek loaded with coral and oysters. The tannic acid is strong enough to kill most bacteria. Water near drinkable.

James, I will donate this specimen if you find a good educational place for it. I collected it and another 75 lbs. from the dry spoil area on what I think is Honeymoon Island. I had a friend that owned a rock shop in Fort Myers, Florida that invited me to hunt for coral in the Tampa Bay spoil area. We drove up from Fort Myers, Fl. and easily found the area. It was covered with people, holes dug everywhere and coral scattered about from the Tampa Bay ship channel. The channel was being dredged wider and deeper and huge amounts of material was being removed and deposited by pipeline slurry. My interest was not what I found but druzy quartz to cut for freeform cabs. I decided to preserve this as a specimen when I noticed the clam sections once the piece was cleaned. I was a science and art teacher at the time so I knew what I found might be useful for "show and tell".

If you know of an educational facility that would be interested in a collection of this coral let me know. I love colorful agates woods jaspers and the like. The fossil coral was the closest source of agate like material near home. It just happened to be a fossil. Fortunately a fossil of not much value to science. Collecting it took me on a journey thru learning about the ice age, beautiful wilderness, great people, the tumbling hobby, interesting geology, artifacts, old bottle finds, other fossils, and the list goes on. For 20 years, and not much has changed. The locations remain a beautiful wilderness and there is a large portion I have not explored.

About Tampa and the islands off the coast in that area - they have been heavily picked over however their remains a layer under the sand covering a vast area. A direct hit from a hurricane could expose 1000's of tons of that coral. The coral layer averages about a foot thick with an average of 5 feet of sand on top of it. And it is illegal to remove the overburden sand by prop washing or dredging to get to it. There is a more sought after 'finger' coral, the lapidarians love it. It gets exposed during excavation projects in and around Tampa.

From images

That would make a really cool counter top! :-)