A genus of small, extinct brachiopods from the early Paleozoic era with shells that lack a pedicle opening.
From Greek 'akron' (tip/summit) plus 'tresis' (perforation/hole). Named because unlike most brachiopods, these shells had no hole for the stalk attachment at the apex.
Acrotreta shells are so tiny—smaller than a grain of rice—but they're some of the oldest identified fossils with hard shells, making them crucial evidence for understanding when life first armored itself about 550 million years ago!
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