In normal, human, terrestrial, domestic urban or rural life, the concept of a chimney is nothing special to people. To some, the romanticised idea of a warm fireplace, to some bringing about thoughts of Christmas, and others simply curiously wondering at such ancient forms of energy acquisition. On a larger scale, like in industry, chimneys are seen as a symbol of pollution and chemical toxicity, with factories pumping clouds of black smoke into the atmosphere to produce whatever they produce. Or even larger icons of destruction, are the monstrous chimneys of Nuclear Powerplants, massive funnels billowing steam reminding us of scale of energy contained and being produced within the facility.
This design, to eject masses of by-products into surrounding environment, long pre-dates human thinking. Coral reefs around the world are filled with its own chimneys, often well over the height of the tallest ape and sometimes several meters in circumference, Barrel Sponges are the towering columns of the marine world. These structures are some of the simplest, and are descendants of some of the oldest forms of life on our planet, and they serve an often overlooked role in saving coral reefs. Above the waves, chimneys direct waste gasses into the air above to dissipate over a wider area and the same mechanism is utilised by the barrel sponge on coral reefs. The reefs of Koh Tao have a diverse range of sponges but none are more impressive and dominating the reefscape than the Barrel Sponge (in this case, Xestospongia testudinaria).