Sea cucumbers are echinoderms from the class Holothuroidea. They are marine animals with a leathery skin and an elongated body containing a single, branched gonad. Sea cucumbers are found on the sea floor worldwide.
 
Sea cucumbers are highly valued by Chinese for their excotic cuisines. So trading of the sea cucumbers has been known as early as 18th century.
To supply the markets of Southern China, Makassar trepangers traded with the Indigenous Australians of Arnhem Land from at least the 18th century and probably earlier. This is the first recorded example of trade between the inhabitants of the Australian continent and their Asian neighbours (source: https://en.wikipedia.org/wiki/Sea_cucumber)
 
Our Sea Cucumbers are caught in sandy beaches around the Natuna and Borneos coastal which still has no contamination.