Octopus

Female octopuses can lay 10.000 to 70.000 eggs after fertilization.

An excerpt from the article 41 facts about octopus

They place them in rock crevices in the form of special strings of eggs. The eggs are then guarded for approximately 160 days when the baby octopuses hatch. In colder waters, octopus eggs can develop for up to 10 months.