Appearance of the marine creature called "by-the-wind sailor"

BLOB

This gelatinous, drifting sea organism looks like a shapeless, floating puddle on the waves.

The "by-the-wind sailor" is a small, free-floating marine creature with a translucent, jelly-like body that often washes up on shores. Its rounded, gelatinous shape resembles a shapeless mass, which is why it’s casually described as a "blob." The clue plays on this visual similarity, using the creature’s nickname to hint at the simple, four-letter answer. No wordplay here—just a straightforward nod to its blob-like appearance.