The Movile Cave in Romania has a unique isolated ecosystem. The bacteria get their energy from chemosynthesis of sulphurs and methanes. This the only known ecosystem on land where chemosynthesis rather than photosynthesis is the primary conversion of energy.

Due to the lack of light, most of the animals in the cave have evolved to lack eyes and skin pigment. Many have extra long antennas to feel around.

In 1996, researchers categorised the animals in the cave. They included 3 species of spider, a centipede, 4 species of isopod (the group that includes woodlice), a leech never seen anywhere else in the world, and an unusual-looking insect called a waterscorpion.

The journey into the cave is extremely hazardous and less than 100 people have been allowed inside.