Hmm yes, it does look like a fish tail.
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attachment=4696]
The dots as microscopic life seems a bit difficult for the 15th century though.
It could just be a spewing geyser?
Could just be a geyser
And i guess i didn't mean microscopic as in unseeable by human eye, i was thinking limestone, but coquina, for instance, would show that it was made of shells.
![[Image: coquina_2.jpg]](https://www.nps.gov/casa/learn/historyculture/images/coquina_2.jpg)