Appearance
The body of P. homarus can reach up to 31 centimetres (12 in) in total length, or a carapace length of 12 cm (4.7 in), but the average is around 20–25 cm (8–10 in).
There is variation in the colouration, which parallels other morphological differences; most animals are dark green and have only very small squamae in the grooves of the abdominal tergites. Other animals are red, and have much more prominent sculpturation in the grooves on the abdominal tergites. The green form is known as the microsculpta form, and the red form as the megasculpta form.

