We found this object (see photo by a sea wall in south-east Thailand. The white substance looks like a folded piece of fabric made out of limestone encrusted with glassy spheres. Only a tiny section of each sphere is attached to the limestone, but they are held firmly in place and cannot be removed with a fingernail. None of them has a surface scratch, which is impressive considering they must have been bashed by waves against the rocky sea wall. What are these tiny spheres?
Natam Tonkul, Bangkok, Thailand
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