**Who left Paleozoic “dumbbells”?**

All over the world, scientists find **dumbbell-shaped fossils in rock outcrops** that **are called Bifungites** and a**re not fossilized animals but burrows left in an extinct creature’s wake**. ⬆️ Most are found in rocks from the more than 300 million years ago.

🪱 Not long ago, [Brazilian paleontologists](sciencedirect.com/science/article/pii/S2950475924000029#bib4), exploring the bed of the Sambito River in northeastern Brazil, found imprints of **small worms** inside Bifungites, indicating that these organisms **produced them**.⬆️

Researchers suggest that:
📌 the that made Bifungites belonged to a group called __Annulitubus__
📌 species in the group lived in the shallow part of the ocean near the shores of prehistoric supercontinents and dug burrows into the seabed.
📌 the Annulitubus worms made these burrows to protect themselves against savage storms or probing predators
📌 the worms potentially wedged themselves into the peculiar bulging or arrow-like ends of the chamber.

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