Scientists have discovered that four new species of deep-sea flatworm-like animals that appear like deflated whoopee cushions and don’t have complex organs have assisted them in solving a complex puzzle regarding the placement of their group on the tree of life.

The latest study involved 12 years of specimen collection and analysis. It has put the new species to a group earlier known by just a single species, and when scientists did so they obtained a clear picture of the evolutionary position held by these animals.

Simple is not the apt word to describe the physical characteristics of these baggy marine creatures. They don’t have any recognizable face or limbs, and their bodies are blobs that appear more like empty socks than animals. Muscular folds have wrinkled them, and are propelled by cilia.

On one end there is a mouth opening leading to a gut sack, but in the back end there is no anal opening.

The species don’t have digestive system, excretory system, reproductive organs, and they aren’t concerned about the same because they don’t even have brains, either. They just have a neural network.

The study researchers said that besides surface appearances, this genus Xenoturbella has always been quite difficult to position on the life tree, since the discovery of the first species, Xenoturbella bocki, in 1950.

Initially, scientists classified them as a flatworm, and thereafter in the 1990s, said that it was a kind of mollusk that suffered degeneration, losing more developed features with time for reaching a simpler form.

The description has placed Xenoturbella nearer to vertebrates and echinoderms, the group of marine life, including starfish and sea urchins, rather than in an earlier evolutionary site at a more far away branch from such more complex animals.