Nudibranch

Saw this 2 Nudibranch mating. Nudibranchs are hermaphroditic, thus have a set of reproductive organs for both sexes, but they cannot fertilize themselves. The genital organs are located on the upper right side of their body.
Nembrotha lineolata grows to a length of about 70 millimetres (2.8 in). The body is slender with a rounded head at one end and a pointed tip to the foot at the other. The exterior of the body is covered with longitudinal wrinkles and there is no sharp demarcation between the dorsal surface and the lateral surfaces. The oral tentacles are thick and long and the large conical rhinophores bear about thirty lamellae and can be retracted. The three large pinnate branchial plumes on the dorsal surface are non-retractile and the anus is located between them. The colouring of this nudibranch is variable across the animal's range. The body colour is creamy-white with narrow longitudinal lines, some broken, in varying shades of brown. Sometimes these lines merge in places giving transverse bands of colour.