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Hi I'm trying find out what kind of rock this is.... I have a chunk the size of akeg of beer looks like muddy coral on the bottom and coral like inside and agatized sponge or coral or something else that once lived....... please let me know I have a lot more photos I couldn't upload

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    $\begingroup$ You can always upload the other photos to a generic image hosting site and add the links in your post ; someone edit will them in. Please do so. But your question misses essential information, so read A guide for asking identify this rock questions and edit it in. $\endgroup$ – Jan Doggen Nov 30 '18 at 20:44
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I am sorry to say, but this is no fossil. Corals would show septa in radial symmetry. Stromatolites are very massive due to the fact, that very thin algae layers are laminated by sand layers. Then the next algae layer grows over the sand, followed by another sand layer and so on. This creates quite massive objects. It's also no sponge. They also create quite massive fossils.

What you have is a piece of calcareous sinter, possibly formed in a cave. If you take a closer look, you will see well developed layers of calcium carbonate. These are formed over long time periods by limy freshwater.

Further information can be found here

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