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Bronzviking

Florida Agatized Sponge or Coral?

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Bronzviking

I found this awesome glittery piece on the beach in Tampa Bay. It is kind of layered and has a cheesecloth pattern on it. It is about 2 x 2 1/2 inches in diameter and about 1 1/4 inches in height. It is lighter than my typical coral finds. It has what looks like 2 bore holes that go right through. I'm not seeing any corallites so I'm leaning towards a sponge. I have 3 photos-- top/bottom and one side view. (Note: photos don't capture the crystallization) What do you think it is? Thanks in advance.

DSC080571.jpg

DSC080601.jpg

DSC080561.jpg

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abyssunder

maybe a glass sponge?

 

Sponge1.thumb.jpg.f0871bc297ef09bf7d5f6db4abab9973.jpg

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Innocentx

This may yet be a coral where distinguishing characteristics have been worn gone. 

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SailingAlongToo

Looks like coral to me.

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Innocentx

I played with your second photo and can see hexagonal shapes here:

 

DSC080601.jpg.15f3ba798e5ad4f526375db9a79ba0b4.jpg.89b489b2f310068db8c18f237edbd527.jpg

 

 

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Al Dente

I think it’s a very eroded bryozoan.

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Tidgy's Dad

Coral for me. 

Interesting piece. :)

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abyssunder

I'm wondering what might be the stellate features in the circled in red areas: septa, spicules, acicular crystals, or something else? :headscratch:

 

601.thumb.jpg.3f9b8b2ccaa08f359f571baa3da46977.jpg

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Harry Pristis

 

Fossil corals from Tampa Bay (at least from the 'Silex beds') do not preserve in this fashion.  On the other hand,  colonial algae might build a skeleton much more randomized than a corallum.  I just don't know enough about colonial algae or sponges to hazard a guess.  Is it calcium carbonate or silicified?

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Bronzviking
1 hour ago, abyssunder said:

I'm wondering what might be the stellate features in the circled in red areas: septa, spicules, acicular crystals, or something else? :headscratch:

 

601.thumb.jpg.3f9b8b2ccaa08f359f571baa3da46977.jpg

Looking under magnification I'm leaning towards spicules or unknown.

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goatinformationist

Shiny like glassy, and light weight?  It looks like pumice to me.

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Bronzviking
1 minute ago, goatinformationist said:

Shiny like glassy, and light weight?  It looks like pumice to me.

No not glassy, sparkly like diamonds. It's lighter than my coral but still has weight and pumice is not typically found in Florida, but thanks for looking.

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Bronzviking
1 hour ago, Innocentx said:

I played with your second photo and can see hexagonal shapes here:

 

DSC080601.jpg.15f3ba798e5ad4f526375db9a79ba0b4.jpg.89b489b2f310068db8c18f237edbd527.jpg

Thanks for enlarging. So what does the hexagonal shapes tell us?

 

 

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ynot
51 minutes ago, Bronzviking said:

So what does the hexagonal shapes tell us?

That it is from a biologic source and is not pumice.

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Innocentx

@Bronzviking  Did you do the fizz test yet?

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Bronzviking
2 hours ago, Harry Pristis said:

 

Fossil corals from Tampa Bay (at least from the 'Silex beds') do not preserve in this fashion.  On the other hand,  colonial algae might build a skeleton much more randomized than a corallum.  I just don't know enough about colonial algae or sponges to hazard a guess.  Is it calcium carbonate or silicified?

I agree it doesn't look like our typical coral. Is there a test I could do to differentiate the two?

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ynot
6 minutes ago, Bronzviking said:

I agree it doesn't look like our typical coral. Is there a test I could do to differentiate the two?

Hardness test would be the easiest, does it scratch a knife blade?

Yes=silicate

No=calcite

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Al Dente

Here's a modern bryozoan that I picked up on a beach in North Carolina. Some of the structure is very similar to Bronzviking's piece (inset).

combined.jpg

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Bronzviking
20 hours ago, ynot said:

Hardness test would be the easiest, does it scratch a knife blade?

Yes=silicate

No=calcite

It scratched a Swiss pocket knife blade. So would that be a hardness of 7?

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Bronzviking
10 hours ago, Al Dente said:

Here's a modern bryozoan that I picked up on a beach in North Carolina. Some of the structure is very similar to Bronzviking's piece (inset).

combined.jpg

The structure looks very similar. Thanks for posting the photo.

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abyssunder

Recent corals or bryozoans are not agatized. Maybe there's a chance for glass sponges, already silicified? :headscratch:

link

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Innocentx

@abyssunder. Great article. Sponges are so unique in their ways.

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abyssunder
20 minutes ago, Innocentx said:

Sponges are so unique in their ways.

I agree with you! :)

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ynot
2 hours ago, Bronzviking said:

So would that be a hardness of 7?

If the only 2 choices are calcite and quartz minerals, yes.

A knife blade (steel) is around 5 on the mohs scale.

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Bronzviking

Thanks for everyone's input. The knife test shows silicate, not calcite. We have many theories; coral, sponge, bryozoan and colonial algae. Should I put this in the unknown pile or do we have anymore IDs? Can you take a look at this piece please? @Johannes @digit @Plantguy

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