Male pregnancy in seahorses?!

Yes, you have not mistaken. The closest thing we can relate to is probably, hermaphroditic animals whose reproductive organs are normally associated with both male and female sexes. This is a common phenomenon in snails and slugs, in which both partners can act as the "female" or the "male".

However, we are looking at an unusual event where the male and female counterparts bear opposite responsibilities to what it would normally be perceived as, particularly in reproduction.
The female seahorse would deposit its unfertilized eggs into the male's body, and to be exact, in the brood pouch on its ventral side. After internal fertilization, the pouch provides the necessary nutrients for the embryo to mature. The eggs then hatch in the pouch, before they are being released into the sea. The father protects the young until they are able to survive on their own.

The rarity of such reproduction has unusual implications on the seahorses' mating rituals and behavioral patterns. They are thought to be monogamous, however, it seems that the females have multiple partners, while the males are only able to mate with one female at a time. As opposed from many other species, the female competes for the male in order to mate. After which, she visits him daily for “morning greetings” during gestation. In reminiscence of courtship, they interact for about 6 minutes, and she swims away and returns only the next morning.