Scientists studying robots encounter many problems in their endeavor, and they usually turn to Mother Nature to solve their problems.

For instance, how would a robot move?

Walking in an upright, manlike position is pretty difficult to achieve, and the most evolved humanoid robot only walks as fast as a clumsy three year old child.

Wheels or tracks are a good idea, but they don't always get you out of slippery roads or through the lunar landscape.

The new generation of robots could walk like insects, all those legs giving them extra support and agility, but what about sliding?

Not a skating robot, a snail robot that could climb walls - slime not included.

A team of engineers from the Massachusetts Institute of Technology (MIT), US and the Catholic University of Leuven (CUL), Belgium, have set a small robot climbing walls in order to compare how natural and artificial snail slimes work.

A snail's slime acts as both a glue and a lubricant, allowing the snail to crawl up walls and across ceilings without falling off. The snail pushes until the structure of the glue underneath it breaks, at which point it glides forward.

When the snail stops, the glue structure reforms - sticking the snail safely to the surface.

The researchers studied how the cycle of glue breakdown and repair works in natural snail slime, but they also studied artificial slimes based on clay and polymers and calculated the ideal slime properties that a climbing robot would need.

The results are promising, since they discovered that the robot could very well climb using hair gel or peanut butter. "Who would have thought that snails could use other soft solids such as mayonnaise or axle grease as an adhesive lubricant to climb up vertical walls?" said Christian Clasen, of CUL, who worked on the study.

Co-worker Randy Ewolt of MIT said: "An important result is that snail mucus per se is not required for robots to climb walls. We can make our own adhesive locomotion material with commercial products... (or by) harvesting slime from a snail farm."

This decision will remain a sticky problem!