The Palm Tree Polyp is great for beginners and helps to take nutrients out of the water! Their polyps are housed in little flexible tubes that are also connected to a mat. These little tubes can be 1/2" to 2" tall (1 to 5 cm), depending on the species. They have 8 tentacles and come in a variety of colors such as green, purple, yellow, white, brown, pinkish cream, or cream with centers that can also be contrasting colors. The polyps can retreat completely into the base of their individual calyx.
The Pulse Coral is one of the most sought after of the Xenia genus! They are either very easy or very difficult and no one knows why! One of my tanks killed them and another tank they flourished! The movement of the tentacles makes them appear to be "clapping" and in certain conditions can almost spread and become plague like! Many put them on equipment to help hide pump inlets, etc. Small additions of iodine are okay, but too much can melt them!
While this video is supposed to be about a mysterious nudibranch, it just so happens to be hanging out on a pale green Tree Coral, Lemnalia sp.! These corals are ridiculously easy to care for, grow and propagate! A small frag can go into a nano tank and kept trimmed if desired! They do not seem to bother other corals if the tank is large enough. Personally, I have a small one in my 75 gallon with stony corals and they are fine. I also keep it under 6" tall!
This video of a Waving Hand Coral has a great and useful narrative! These corals can be kept in nano tanks if they are kept cut back or are great in a large aquarium. Imagine the entire back wall covered with these! That would be mesmerizing! Low to moderate lighting is best and adding zooplankton is helpful for growth. If light is higher, acclimate them slowly and watch them for signs of stress. Unlike Xenia, they do not melt away.