Southern rock lobsters, also known as spiny lobsters, are not actually true lobsters, like the ones you might find on a dinner plate, but instead belong to a more distantly related group called the Achelata, which literally means without claws. Achelates lack the pincer like claws of true lobsters and crayfish/crawfish, which have claws on their first few walking legs, including the big, conspicous ones that people like to eat. Instead, achelates have modified their appendages in other neat ways. In the case of the spiny lobsters, belonging to the family Palinuridae, they have highly robust basal segments of the antennae, as you can see here. Why? I'm not sure, but it may have something to do with their foraging ecology. The palinurids closest relatives, the scyllarids, otherwise known as slipper lobsters, have even more derived modifications of their attenae, in which the second pair of antennae have few, highly robust, widened, flat plats, which likely aids them in their bottom-dwelling lifestyle.   For the story of this individual lobster, see: www.sheddaquarium.org/2200.html