Fissures and sulfur fissures

Add fissure blocks, like a Sulfur Fissure. Similar to the gyser the fissure would occasionally spew gas. The sulfur fissure would generate in the sulfur caves, with variants generating near lava pools at -50, and only exposed to air. These would make a hiss of air when they go off. In the sulfur cave it would really make it feel more alive, like there is geothermal activity beneath your feet.