Hydra babies come in two types, buds and hatchlings. Buds grow like tree branches out the side of the main trunk of their parent. Eventually the branch is almost as big as the trunk, and they separate, and you have two hydra. Eggs also grow on the sides of their mothers, but they need to be fertilized by free-swimming sperm that are released by male hydra. Then they make a hard shell, detach from the mother and settle down to wait some weeks or months before a tiny hatchling wiggles out. Where the buds are like small copies of their parents, the hatchlings are tiny and genetically novel individuals. They are too small to easily eat the crustaceans we usually feed the adults and buds (Artemia) so we feed them mashed Artemia, except they like their food alive. I have ordered rotifers to see if they will eat those, as they are smaller and softer than the Artemia.
I find myself looking forward to having rotifers in the lab again. They are just so familiar at this point.