Giant cuttlefish (Sepia apama) male (top) guarding an egg-laying female (bottom). After mating, the female lays numerous eggs in individual egg cases, attached to plants, rocks or corals. The male will often guard the female while she is laying eggs, to prevent another male from approaching. The eggs harden after they are laid, which makes them difficult for predators to extract from the coral. The eggs hatch in around 38 to 40 days. Photographed off Spencer Gulf, Wyalla, Australia.