How does it happen?
Dumbo Octopus
Like most living animals, most Mollusk reproduce sexually. Meaning, there must be a male and female parent for it to work. Keep in mind that I said MOST. Some, like the mussel or the clam, are asexual. This is because they are Hermaphrodites.
A hermaphrodite is a creature that has both male and female reproduction parts.
A hermaphrodite is a creature that has both male and female reproduction parts.
Graffiti Snail
Like clams and mussels, snails are also hermaphrodites. However, they prefer to find another snail to mate with instead of going it alone. This being said, they can probably switch the roles of male and female whenever the please.
Octopus Eggs
Mollusk can have both internal and external fertilization, but it really depends on which class their in. For instance, clams are hermaphrodites and therefore release their eggs out into the ocean and then fertilize them, while Squids, who are divided into separate sexes, will have internal fertilization.