Last year, VOA Learning English wrote about a strange "Ice Monster" caught on video in Alaska.
Many internet users thought a piece of frozen rope in a river was actually a monster, like the Loch Ness monster in Scotland.
Now there is a new water-related mystery.
Over the weekend, people on a Florida beach found a half-eaten shark.
Officials in Volusia County said the shark was a blacktip or spinner shark, slightly less than two meters long.
People are trying to figure out what took a bite out of the shark.
The county is home to the well-known Daytona Beach and has a large number of shark reports each year. The Orlando Sentinel newspaper reported in late 2016 three surfers in the area suffered non-fatal shark bites on the same day.
Florida wildlife officials say two large great white sharks were seen in the area this winter. The sharks were a little more than four meters long.
Many news organizations posted about the shark discovery on Twitter.
Some comments on the stories included: "just a reminder there is always someone bigger than you."
The Florida Program for Shark Research is part of the University of Florida. In response to the story, the program said "it's a shark-eat-shark world out there."
One Twitter user wrote "megalodon got him!"
Megalodon was a predecessor to today's great white sharks, thought to have lived many millions of years ago.