The Lion's Mane jellyfish is the largest known species of jellyfish in the world. These ones were filmed in waters around Mull, Scotland last week. They are fairly easy to spot as they spend most of their time near the surface of the water. The Lion's mane jellyfish appears in the Sherlock Holmes short story "The Adventure of the Lion's Mane" published in The Case-Book of Sherlock Holmes. Holmes discovers at the end of the story that the true killer of a school professor who died shortly after going swimming (shouting "the lion's mane" before he succumbed.) was actually this jellyfish.