Question: What do butterflies, lobsters and scorpions have in common?
Answer: They all wear their skeletons on the outside!
This is called an exoskeleton and all creatures that have their structure on the outside are included in the phylum of Arthropods.
A large majority of arthropods belong to the three main groups:
Insects – Ants, Aphids, Beetles, Butterflies, Cicadas, Cockroaches, Dragonflies, Fleas, Flies, Grasshoppers, Leaf hoppers, Lice, Mayflies, Praying mantis, Stink bugs, Silverfishes, Termites, Stick insects
Arachnids – Spiders, Scorpions, Ticks and Mites
Crustaceans – Barnacles, Brine shrimp, Crabs, Crayfish, Krill, Lobsters, Shrimp or Prawns
Photo credit here.