Spinoloricus is a genus of marine worms belonging to the phylum Annelida. These unique organisms are characterized by their elongated bodies and the presence of specialized structures called "spinous processes," which aid in locomotion and anchoring in their environment. Spinoloricus species are typically found in deep-sea habitats, where they play a role in the benthic ecosystem. Their adaptations to extreme conditions make them an interesting subject of study in marine Biology.
One example of a species of Loricifera is Spinoloricus cinziae. It is a marine microscopic animal found in the Mediterranean Sea, known for its protective outer shell made of overlapping scales. These organisms live in the sediment at the bottom of the sea and have unique adaptations to survive in extreme environments.
I think you are meaning if organisms don't need oxygen are they still living things? The answer would be yes they are. There are plenty of anaerobic bacteria around. Anaerobic meaning that it lacks oxygen. Bacteria are single cell organisms that are very much alive, but there was also a recent discovery in 2010 where they discovered a multicellular organism that doesn't require oxygen as well it's a species of Spinoloricus.
Slug and other gastropods have what's called an open respiratory system. Humans, for comparison, have a closed respiratory system. Essentially, slugs "breathe" through the pours of their skin. Oxygen enters and carbon dioxide exits.