Photo of Animalia: species: Heteropsammia cochlea (Lizard Island Field Guide)

A sipunculan worm, Aspidosiphon (Aspidosiphon) muelleri, is an obligate commensal with Heteropsammia cochlea. It lives inside the skeleton and can extend its proboscis through a hole in the base of the coral to move the coral and prevent it from becoming buried.

© Anne Hoggett