There’s an interesting article in the NYTimes about the search for the creature that leaves this pattern on the bottom of the ocean.
This pattern was first seen in ancient rocks and were believed to have been made by some sort of extinct creature. But in the 70’’s it was seen in fresh sediment near the Mid-Atlantic ridge. That means that the creature still exists and that it would be possible to catch one and answer the questions about what created these strange fossils.
Jerry Coyne’s blog has some more details.