They look real to me. usually the fake ones are "too round". Try taking some tank water in a small container, and squeeze them out really good a few times, then put them back in the tank. It will take some time for microorganisms to grow on them for shrimp to eat, but they should catch tiny food particles which the shrimp should go for. Ive found shrimp aren't as crazy for marimo as everyone makes them out to be, yes they like them, but I don't think they really go crazy for them.
Welcome to the forum. Yes they look like marimo moss balls. Could you please explain what you mean about the shrimp? My ghost shrimps will pick little bits of food off them but do not hide in them if that is what your asking. What kind of shrimp do you have? Alison
To clean them I gently squish them in some clean dechlorinated water, and the gently roll them in my hands as though you're making a meatball and put them back in. They can come apart if you are too rough with them so the operative word is gentle, Don't try to make a pancake out of it. He He. Alison.......Yes that takes time. Did they charge you the price of the amano for the ghost shrimp they gave you by accident?