Complex sentence: Most are small, grey to white coloured animals with rigid, segmented exoskeletons, two pairs of antennae, seven pairs of jointed limbs on the thorax, and five pairs of branching appendages on the abdomen that are used in respiration.
Split into simpler sentences: Most are small, grey to white coloured animals with rigid, segmented exoskeletons. They generally two pairs of antennae, seven pairs of jointed limbs on the thorax, and five pairs of branching appendages on the abdomen that are used in respiration.