Most pirates stole coins to spend, not bury. One pirate who did bury treasure was Captain Kidd. In 1699, he hid gold and silver on an island near New York. People have dug up some loot, but more may still be concealed.
1) What does the word "concealed" mean? *
According to pirate lore, pirates who buried treasure would make a treasure map. On the map, they would mark an "X" to designate where they had put their treasure. In reality, pirates probably did not make treasure maps, let alone bury treasure.