Yellowhead jawfish are mouthbrooders. After courtship, the male fertilizes the eggs and collects them in its mouth- hundreds of them- incubating them until they’re ready to hatch. A few days later, the eggs hatch and the fish fry (babies) swim off. Only the male takes on this responsibility. While the male is holding the eggs, he cannot feed. He’s underweight by the time the eggs hatch, and needs some time to recuperate.
As for sea hare eggs, they’re enveloped in a delicate membrane, packed into capsules, and laid as noodle-like strands.