Arachnorodent
Noun. Cross between spider (arachnid) and a rat (rodent), producing the Arachnorodent. These common paests have eight legs like all spiders, but instead have the body of a rat, with the complex eye structure of a spider. They live in walls, particularly the walls of innocent home-dwellers' bathrooms, and poduce scratching noises. Arachnorodents are also seasonal, only infesting homes during the cold months of winter and early spring.
"I was taking a shower last night, and the Arachnorodents were running up and down the insides of the bathroom walls"