A Trade

There's solid wood that had a smooth and lustrous surface and would not rot for thousands of years, even without undergoing any special treatment. Along with it was plenty of shellfish in the coastal area that had toxic and inedible meat once the shell was plied open. However, it had this round, enormous, smooth orb that resembled the pearls on Earth within. Lastly, there are the organs of the beasts that would greatly benefit some male functions once ate it. 

In the mainlanders' eyes, all of these beautiful items in the Hellfire Archipelago were basically gold. Many of the usual things that were invaluable in the eyes of the Hellfire tribesmen were extremely precious in their eyes.