Vicules are large arachnids that grow up to the size of a basketball. They live in burrows which they typically dig themselves, and they line them with silk from their spinnerets. They emerge from their burrows at night to hunt large insects and small vertebrates, which they ambush and then inject with venom. They are generally slow and docile, and adults only need to eat once every few weeks. While venomous, they typically only bite their prey. If they feel threatened, they will instead use their hind legs to flick the hairs on their abdomen into the face of a predator (or unsuspecting vicule keeper). These barbed hairs are called urticating hairs, and while not especially dangerous, they can be painful!

Despite their large size, vicules don't require a lot of space, and they are generally low maintenance pets. They are long-lived and only need to eat occasionally, and they are typically fed a diet of feeder roaches and mice. Vicules tend to be shy and skittish - stories of them fleeing from their prey or panicking after stepping on their own feet are very common! However, with patience and care, they can learn to be handled. They are very soft to hold. It's important to keep a vicule close to the ground when handling, as they are built to be ground-dwelling and can be seriously injured by even short falls.

The mark on their abdomen is called a "heart mark". Not only is it heart-shaped, but it's also roughly positioned above their real hearts!