The rough knob-tailed gecko (Nephrurus amyae) is the biggest of the knob-tailed geckos reaching 15cm. These unusual lizards are endemic to central Australia. They are voracious predators and have a preference for nocturnal gecko species. The function of the weird little tail is not yet clear. Research has shown that the cells inside the tail appear to be very different from any others and may have some sensory role.