Not all animals with long gestation periods are large mammals. There are some worm-like animals that bear live young, including the velvet worm. This bizarre-looking creature carries its young for as long as 15 months. Despite the name, they aren't true worms and they aren't made of velvet. Their bodies are covered with sensory hairs, which gives them a velvety appearance.
They are considered close relatives of both arthropods (spiders and insects) and true worms (like the earthworm) — making them especially interesting to paleontologists.