A deep-sea mineral spire, known as Bikpela, (Big Bug in Tok Pisin, a creole language spoken throughout PNG) and first discovered in 2000 by both Australian and Papua New Guinea researchers, is going on display for the first time. Taking pride of place at the Australian National Maritime Museum’s exhibition Ultimate Depth: A Journey to the Bottom of the Sea, the spire has given valuable information about the undersea world.

Found by Dr Ray Binns and his team in the Manus Basin off the coast of Papua New Guinea, the spire has been revealing valuable information about hydrothermal vent systems. Volcanic vents rise from the seafloor, which in turn fuel the basin’s hydrothermal vent systems. Spires and chimney-like towers rise, venting minerals and heat into the sea.

Bikpela is the largest found spire, standing at 2.7 metres tall and weighing a whopping 970 kilos. Bikpela has since been cut in half lengthways, revealing its complex internal structure, as a rare type of hydrothermal deposit that is different from those previously discovered.

Formed when heated fluids burst through the seafloor and mix with the seawater, the chimneys grow larger layer by layer. Bikpela’s core is framed by opaline silica, barite (barium sulfate), with zinc, iron, lead and copper sulfides, as well as significant trace amounts of silver and gold. “It was clearly quite different from the high temperature, sulfide-rich chimneys known as “black smokers” that the team had collected elsewhere in the Manus Basin and dominate hydrothermal vent fields elsewhere,” Ray said.

The internal structure of Bikpela reveals key clues about the growth cycles of the chimneys. Bikpela began with microbial activity, before several stages of high-temperature precipitation of sulfide minerals, and even a dissolution and collapse which created a large cavity in its core.

According to Ray, recovering Bikpela and studying it has greatly increased our understanding of low-temperature hydrothermal deposits found alongside metal sulfide “black smokers” on active volcanic seafloors. Black smoke chimneys usually last anywhere between a few years to decades, depending on the geological and environmental conditions. Shifts in tectonic activity or structural weakening can cause collapse or the spire to become inactive. Some chimneys do return if venting resumes, making them fascinating deep-sea enigmas.

“What’s exciting is how much it tells us about the relationship between tectonic activity, hydrothermal fluids associated with submarine volcanoes, and biological processes in forming these chimneys. We don’t get to see pieces like this often. It’s a real privilege to bring them back to share with others.” says Dr Joanna Parr, a geochemist and senior scientist with CSIRO’s Mineral Resources team.

Since its discovery, one half of Bikpela had been displayed at CSIRO’s Kensington office in Perth (The other half is held by Museums Victoria). However, after all this time, Bikpela has been moved to the Australian National Maritime Museum in Sydney, NSW, to join a new exhibition opening in 2024, where visitors will encounter artefacts and stories from the seafloor, showcasing the unique ecosystems found kilometres below the surface.