Christmas moss (Vesicularia montagnei) is a popular aquarium moss in the hobby. It get it's name from it's bushy appearance and triangular shaped leaves, resembling (obviously) a Christmas tree!
Christmas moss is well known for its versatility, as it can survive in a wide range of tank parameters. It's also a super easy plant that you'd likely have to go out of your way to kill - making it great for beginners, experts, and everyone in between.
Much like other mosses, Christmas moss provides a number of benefits to your aquatic ecosystem - including oxygenation, a place for smaller fish to hide, and filtration. On top of that, it's a really cool plant that can be used for carpeting or tying down to hardscapes.
Compared to other mosses, Christmas moss will typically grow slower and flatter than java moss and flame moss. And while it can survive in a wide range of temperatures and lighting, it does it's best work in warmer waters and high lighting. CO2 is not necessary, but as always it will provide a boost.