Abalones are dioecious (separate male and female sex) as abalones develop their eggs and sperm in gonads located under the soft skin visible between the foot and the shell.
There is no sexual dimorphism of the shell structure and so the sexing of abalone cannot be done based on the external differentiation and is only determined through the visual inspection of gonads which could be seen if the foot and mantle are forced away from the right side.
Male gonads tend to be from white to creamy beige in color while females’ ovaries are usually darker. The photos in this post belong to Omani abalone, Haliotis mariae in which male gonads (left) are creamy white, while females have greyish-green gonads (right). However, in spent females, the color of gonads may fade.
Like all abalones, Omani abalones are broadcast spawners where both male and female release their gametes directly in the water whereas egg fertilization and embryonic development take place.