Skeleton shrimp are skeletally thin and often have ghostly transparent bodies. They grasp algae with their spindly rear legs, while their front legs form large "claws" used for grooming, defence, and capturing prey. Luckily, they only grow to a couple of centimetres (~1 inch) long.

A sea pen may look like an underwater quill, but it's actually a colony of individual polyps — one polyp becomes the stalk of the sea pen and the bulb that attaches it to the sea floor, while the rest form feathery branches. Some sea pens have only a few polyps, while others have as many as 35,000.

A silkworm wraps itself in a fluid substance from its silk glands that hardens to become a cocoon — this cocoon can be unravelled to a single strand reaching lengths of 1.5 km (1 mile). Inside, it "digests" its own larval body (called histolysis) before building up the body of a silkworm moth.

The coconut octopus carries seashells or coconut shells beneath its arms as it travels — using a few of its arms to hold the shells and the others to walk awkwardly along the sea floor. If this octopus encounters danger, it assembles the shells around itself, forming a kind of armour.

The common cockchafer spends its first 3 to 5 years below ground, growing as a larva. Then, all at once, these beetles emerge as adults in great numbers during spring. They clumsily buzz about, using their frilly antennae to find mates and reproduce — they live for only 6 weeks in this form.