AP:
The Great Lakes’ frigid fresh water used to keep shipwrecks so well preserved that divers could see dishes in the cupboards. Downed planes that spent decades underwater were left so pristine they could practically fly again when archaeologists finally discovered them.
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The creatures have covered virtually every shipwreck and downed plane in all of the lakes except Lake Superior, archaeologists say. The mussels burrow into wooden vessels, building upon themselves in layers so thick they will eventually crush walls and decks. They also produce acid that can corrode steel and iron ships. No one has found a viable way to stop them.