What two very different groups of crustaceans are commonly referred to by the moniker "sea cockroach"?

Answer

Giant Isopods and Sea Slaters (genus Ligia)

The confusion surrounding the term stems from it applying to the massive, deep-sea dwelling Giant Isopods and the much smaller, shore-hugging crustaceans belonging to the genus Ligia, known as sea slaters.

What two very different groups of crustaceans are commonly referred to by the moniker "sea cockroach"?

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