The rock was quite compelling, thanks to its surprisingly light weight and faint waxy texture, so young Charlie decided to take it home. As it turns out, the weird rock was actually not a rock at all, but an incredibly rare substance called ambergris, which is, essentially, a very valuable piece of whale poop.Charlie's 1.3-pound piece of ambergris is estimated to be worth somewhere around $65,000.he rock was quite compelling, thanks to its surprisingly light weight and faint waxy texture, so young Charlie decided to take it home. As it turns out, the weird rock was actually not a rock at all, but an incredibly rare substance called ambergris, which is, essentially, a very valuable piece of whale poop.