A Tonnchenform, described by Clara Oswald as a soft and slightly wet jellybean with suckers all over its body, was a creature that lived in outer space. Tiny hands, or possibly feet, lined its body on either side. While she recognised what may have been a head, it had no recognisable face, just a large sucker in the middle, where a mouth ought to have been.
As the Eleventh Doctor explained, they were similar to tardigrades on Earth. It only ate bits of flotsam and jetsam in space. While the Doctor said there were billions, they were so spread out in such a massive universe that you only ever saw one in the wild once in a lifetime. In all his lifetimes, the Doctor had never seen one before.
The Doctor found the Tonnchenform adorable, while Clara decided on disgusting, but kept this to herself. He hadn't considered, though, that it might eat them, as flotsam and jetsam. (PROSE: Normality)