In 2006, two species of chiton, living on bottles buried in the sediment, were discovered by divers during a ???Clean-up Australia??? dive at Bicton Baths. This was unexpected, as chitons are considered to be a fully marine class of mollusc. Chitons are known to harden their teeth (radulae) with iron oxide minerals, and the question was raised as to whether heavy metals, present within the river sediments, could make their way into the teeth. While important in terms of the tooth biomineralisation process, metal contamination in chitons could also be used as a measure of ecosystem health. Furthermore, the distribution of this marine species within the estuary may be useful for evaluating changes to benthic environments resulting from sea-level rise attributed to global warming. Accordingly, an underwater survey was conducted to ascertain the diversity and distribution of chiton species in the Swan River Estuary, and determine whether a relationship exists between the levels of heavy metal contamination in chitons and the sediment.