(Photo: courtesy of Phoebe Camm, Great Keppel Islands, Queensland)
These are not true Caterpillars, and are not even insects.
Sandworms live in the sea in burrows in the sand. They feed on seaweed and dead sea creatures. They have have segmented bodies, with two parapodia bearing bristles each side of each segment. The animals can grow to a length 5 cms.
They can grow to a length exceeding a metre.
They are not poisonous, but can give a nasty bite.
(written 13 June 2018)