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n. A castlelike structure built of wet sand, as by children at a beach.

n. Something that lacks substance or significance.

n. A sculpture made of sand and resembling a miniature castle; typically, but not always, made for fun by a child on a beach.

"It's a home of sorts, occupied by a colony of Phragmatopoma californica, otherwise known as the sandcastle worm."

Wikipedia article on sandcastles   

multisport    environment-destroying    union-busting    dog-eat-dog    free-style