Photos of Pennichnus, Eunice aphroditois and its burrow. (a) Vertical section of the upper part of Pennichnus formosae. The funnel top (yellow line), disturbed zone (dashed red lines) and feather-like collapse structures (dashed white lines) are visible. (b) Vertical section of the lower part of Pennichnus formosae (S = start and E = end of the burrow exposure). (c) Photo of Eunice aphroditois (Bobbit worm) (photo courtesy of Ms. Chutinun Mora). (d) Eunice aphroditois burrow entrance in the intertidal zone (photo courtesy of Ms. Chutinun Mora). (e) Plan view of the upper part of Pennichnus formosae. In both (d) and (e), the shaft of the burrow (white arrow) and surrounding concentric layers (dashed white lines) are visible. Scale bar: (a–b) = 10 cm; (c–e) = 1 cm. Photos without drawings are included in Supplementary Fig. S5.