Tiny spotty sea slug discovered by accident

Scientists have discovered a tiny underwater sea slug, that's smaller than a grain of rice.

The new species, called Thecacera sesama, was found by chance off the coast of Taiwan.

The unusual creature is see-through with black and yellow spots which look a little bit like sesame seeds - which is how it got its name.

Experts say the slug measures less than three millimetres in length and is almost invisible to see.

The unexpected discovery was first made seven years ago by a student researcher, who spotted the teeny sea slug during a diving trip.

What makes the find even more remarkable, is the fact that weather conditions make diving in the waters where the creature was observed only possible for about four months of the year.

A team from the National Taiwan Ocean University, National Museum of Natural Science and National Taipei University of Education got to work to try and identify the unusual creature.

As a result, it took scientists a bit of time to be able to confirm that it was indeed a completely new species of sea slug.

Experts say that Thecacera sesama feed on even tinier underwater creatures called bryozoans, which are sometimes nicknamed "moss animals" because they look a bit like underwater plants.

Even more surprisingly, the team think the moss animals the sea slugs eat could also be a brand new species that hasn't been properly studied yet.

Discoveries like this show that that oceans can still hold many mysteries, researchers say, and they believe there could be more tiny species in the area waiting to be spotted.