purple sock

plural purple socks

1. rareAny of the genus Xenoturbella of marine deep-water flatworm-like animals of the phylum Xenacoelomorpha.

   [See title]

   2016 February 4, Rob Crilly, “Scientists decode riddle of deep sea 'purple socks'”, in Chris Evans, editor, The Daily Telegraph, London: Telegraph Media Group, →ISSN, →OCLC, archived from the original on 16 Jan 2026

   3 more examples

   [see title] The animal, called Xenoturbella, is so bizarre that for 60 years researchers could not work out what it was - or where it fitted into the family tree.

   2016 February 3, Rebecca Morelle, “Mystery of deep-sea 'purple sock' solved”, in BBC, archived from the original on 25 Sep 2025

   She said they had quickly nicknamed it the “purple sock” because it was so difficult to describe the shape of the “really weird” creatures to people who hadn’t seen them.

   2016 February 4, Georgia McCafferty, “Deep-sea ‘purple sock’ provides clues to early life”, in CNN, archived from the original on 07 Dec 2024

   […]: the purple sock has no gut, no teeth — it's just a hollow bag. […] Rouse and colleagues named it Xenoturbella.

   2021, Helen Scales, The Brilliant Abyss: True Tales of Exploring the Deep Sea, Discovering Hidden Life and Selling the Seabed (ebook), Bloomsbury Publishing, →ISBN, unnumbered page

2. Used other than figuratively or idiomatically: see purple, sock.