Acorn worm

Expert notes

Acorn worms are benthic marine hemichordates that live in U-shaped burrows and excrete characteristic coiled, spaghetti-like sand casts on intertidal flats. — The image shows a continuous, coiled fecal cast of processed sand; unlike the discrete, spherical sand pellets arranged in radial patterns by the [Sand bubbler crab Wikipedia](https://en.wikipedia.org/wiki/Sand_bubbler_crab), this extruded pile is the classic surface trace of a burrowing acorn worm (or potentially a lugworm) in a coastal intertidal seagrass habitat.