A former island in the middle of the Río de la Plata between Argentina and Uruguay, or a type of layered rock formation (stromatolite).
From German 'Strom' (stream/river). Isla Martín García was briefly called 'Strom' in various historical contexts, though this usage is not standard.
Stromatolites are ancient layered rocks formed by microscopic bacteria—some are 3.5 billion years old and are some of Earth's oldest fossils, preserving the earliest evidence of life!
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