You are describing insects.
All insects have 6 legs, one pair of antennas and three body sections.
Some examples are:
The common ANT.
Scolopendra is an arthropod. It has a pair of poison claws in the anterior end which are modified first pair of legs.
It has 1 pair of antenna and 1 pair of antennae, people get confused and think it has 2 pair of antenna.
That'd be an arachnid, most likely a spider. Spiders have a cephalothorax ('head chest', exactly what it sounds like) and an abdomen (butt, containing vital organs), and four pairs of walking legs.
If they are grouped into sets, the ladybird, or ladybug has about 8 body parts. There is the head, thorax, abdomen, sets of legs, a set of antenna, the wings, compound eyes, and a mandible.Ladybugs have many of the same body parts that make up other insects: a head, a thorax and an abdomen with three pairs of jointed legs, one pair of wings, one pair of antennae, compound eyes, and a small mandible
It's two per segment
Arthropod is a really general classification; it's a phylum, man, there are a whole lot of disparate critters that fall under this category. From wikipedia: "An arthropod is an invertebrate animal having an exoskeleton (external skeleton), a segmented body, and jointed appendages."
a millipedes structure is it has two body sections, and many pairs of legs as in alot the two body sections consist of a head with one pair of anntenae and a long abdomen with many segments.
Insects
yes
Crustaceans are arthropods characterized (and classified) by their biramous (branching) appendages, which include two antenna pairs. The smaller set are referred to as antennules. All other arthropod groups have one pair except chelicerates and proturans, which have no antennae.
yes
The arthropod body plan has a great deal to do with how they are classified. Insects are hexapods with three body sections, a head, consollidated thorax with three leg pairs, and an abdomen. The chelicerates, like arachnids, have two main body sections and eight legs. Myriapods have up to hundreds of sections each with a leg pair. Many crustaceans are decapods, have ten legs, often a fused cephalothorax and articulated abdominal segments like lobsters, crayfish, shrimp, prawns and krill; similar is true of crabs except the short abdomen (tail) is folded up beneath the thorax. Trilobites (now extinct) are named for having three longitudinal lobes.