Really what kind of moss was it?
Sphag will grow, I dont think its possible for sphag to not grow if its kept wet lol.
I have sphag growing where a plant died but the moss survived and is still growing... Stuff is like a weed.
I like Serps vids, however the mosses he has there, like the carpet moss, sheet moss, and reindeer moss, I have all those as well they seem alive (hard to tell with reindeer moss) but they defiantly are not growing. My sphag dies, then grows back x10 though lol.
I think growing moss is a practice of patience more than anything. Ferns too like Snitz said. I have some Tuberous sword ferns in my Panthers viv. I put one in and with in a couple weeks it was nothing but sticks.
I let it be and got another to try again. Now months later, the second one is almost down to sticks, and the first one has all new leaves and shoots and is looking good. I think those water hungry ferns and mosses just like to die back, and then start to regrow. I think with those ferns as well, they focus more on roots. I wanted to move one the other day, that things roots no joke almost went to the other side of the Viv, at least 3ft look root on it. I heard they were like weeds and may strangle other plants, I am going to keep an eye for that. I am okay with if they want to pop up all over, but not okay with them killing other plants.