Sea apple - Sea apple is a common name for the colorful and somewhat round sea cucumbers of the genera Paracucumaria and Pseudocolochirus, found primarily in Indo-Pacific waters. Sea apples are filter feeders with tentacles, ovate bodies, and tube-like feet. They can release their internal organs or a toxin into the water when stressed.
Kawah Ijen's "Blue Lava" isn't the lava itself, but is due to the combustion of sulfuric gases in contact with air at temperatures above 360°C. There's so much sulfur, that at times it flows down the rock face as it burns, making it seem as though blue lava is spilling down the mountainside. But because only the flames are blue, rather than the lava itself, the effect is only visible at night—during daytime, the volcano looks like any other. And it was sooooo beautiful