Eophyton toolmarks from the early Cambrian Mickwitzia Sandstone of Sweden were examined to assess the characteristics of the Eophyton producer. Based on these observations, the producer is inferred to be an organism carrying a large, neutrally buoyant frond-like structure or crown of tentacles that acted as a sail in water currents. Attached to this sail, possibly via a stalk, was a smaller structure with a diameter ranging between 3 and at least 100 mm, weighted with sediment contained in its interior and/or adhering to its exterior. This weighted anchor plowed the Eophyton furrow while the organism was dragged by water currents, probably in connection with storm events. The anchor was roughly discoidal in shape, with a perimeter that carried small tubercle-like projections and a few deep folds, and was sufficiently flexible to sag against the bottom under its own weight. Psammocorals have been proposed in the literature as possible Eophyton producers. Among the psammocorals from the Mickwitzia Sandstone, Protolyellia can be dismissed as an Eophyton producer, while Spatangopsis cannot be firmly excluded but does not fulfill all morphological requirements. Remaining possibilities are an, as yet, unknown psammocoral with a non-cemented sand skeleton, an actinian-like cnidarian, a seaweed or a kelp-like alga.
- Mickwitzia Sandstone