A male Hapalochlaena lunulata (left) has mounted a larger female and is in the process of passing a spermatophore to her. Just below the female's eye you can see his hectocotylus inserted into her mantal cavity. The grove on the hectocotylus down which the spermatophore passes is faintly visible.
Note: H. lunulata always have a blue line running through their eye. All the other blue markings are rings. To identify an individual in a photo, just look for the eye stripe.