The deepest regions of the Melidoran oceans are carpeted in a thick layer of Ice VI. This type of ice is different from Terran ice, as it only forms under extremely high pressure. The Terran oceans are not deep enough for it to form, but Melidora's oceans are.

At first glance, the ice plains appear to be a barren, featurless expanse of white. But there are creatures here. Not on the ice, but within it. Inside the ice sheet, volcanic plumes, originating from deep inside Melidora's mantle, have melted regions of the ice to create a network of hollow caverns. These caverns are teeming with life. Some stretch for hundreds of kilometers under the ice.

The Ventscraper is a curious creature that lives in Fossa Grandis, a huge trench lined with ice plains and caverns. It closely resembles some sort of large Terran insect. It has six legs, antennae-like feelers on its head, and crushing mandibles. However, Ventscrapers have endoskeletons and backbones, unlike Terran insects. In fact, the Ventscraper is part of the lineage that gave rise to Melidoran land vertebrates hundreds of million years ago. It has hardly changed since that time, making it a sort of living fossil.

The vents spew out copious quantities of hydrogen sulfide, and microbes react this compound with dissolved oxygen from the water and carbon dioxide to produce simple carbohydrates. These microbes are the bedrock of all cavern ecosystems. Using their powerful mandibles, Ventscrapers graze the microbial colonies. Whole herds of them can lay waste to a vent colony. But microbes are hardy, and they soon reestablish themselves in great numbers.