Planaria (flatworms) are immortal - at least that's what Aziz Aboobaker says.

This is because the worms are full of stem cells and can regenerate from any injury. Cut one if half, and two worms will take its place!

In the video above, Aziz discusses his work while looking for worms in a sewage outlet behind the Queens Medical Centre.

Due to a special feature on YouTube, this video is the most-watched produced for Test Tube thus far.