This is a concretion, a chemical accumulation of minerals around some sort of nucleus that stimulated the accretion around that object, which is usually some sort of decaying organic matter. If you didn't already, you should break a few of these open to see what neat fossil material might be inside. Cheers
PBase Server Error
ERROR: 500
NOTES: [hset] LOADING Redis is loading the dataset in memory, at /usr/local/share/perl5/Redis.pm line 268.
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ERROR: 500
NOTES: [hset] LOADING Redis is loading the dataset in memory, at /usr/local/share/perl5/Redis.pm line 268. ,
PBASE_ENV: production
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