The trapdoor spider (Liphistius malayanus), which is about 1.75 inches (4.5 centimeters) across, is an ancient creature, part of a genus that may date back as far as 360 million years to the Carboniferous period.
It has lasted that long by hiding in cave walls in Malaysia, where it camouflages its nest with a trapdoor fashioned from mud and dirt, attached to six to eight signal threads. The spider waits underneath with its legs touching the threads. If an unwary insect lands on that spot, an alarm is tripped and the spider rushes out and grabs the victim and drags it into its lair. Fortunately, it isn't big enough to grab you [source: Liz Price].