This chunk that looks like yellowish rock is ambergris – a polite term for solidified sperm whale vomit. The substance is sought after with perfume makers as it helps to prolong the scent of the perfume. A schoolboy from UK has found the extraordinary large 600 gram piece of ambergris, which is worth about $60,000.
He probably picked it up because it's weird and gross looking.
Parents could have googled it when he brought it home...