As many other technologically advanced species, the Anu use technical assists to do simple menial tasks. Anu engineers developed a type of organic robot, fully artificially created but from biological materials, to help them in day to day activities. These robots, known later by humans as the grey aliens, were very long lasting but fairly delicate in their functioning. They had to be created and programmed one by one, by engineers specialised in this technology.
On a small research ship like the one that came to Earth, the grey were used for maintenance tasks. There would be one or two crewmembers on the ship with the ability to create them and do repairs.