First developed in 1949 by William Grey Walter, an American-born neuroscientist living in England, these "tortoises" boasted a light sensor, marker light, touch sensor, propulsion motor, steering motor, and protective shell. Today, they are considered early examples of robots able to autonomously explore their own environments. They even had some smart capabilities like the ability to steer toward a light source when running low on power. This led to intriguing behavior when they "saw" their light own light reflected in a mirror. Walter claimed that this, "might be accepted as evidence of some degree of self-awareness."