A small plant with thorny leaves.
Fissidens fontanus or the phoenix moss is a real aquatic moss that can attach itself to wood or rock. The leaves are 3 to 5mm long and dark green.
It can survive in non-CO2 injected aquariums, but does better with good CO2 and relatively high light levels. This moss can grow from small particles and even grows back if the wood piece it colonized is allowed to dry out. It can even be seen growing on aquasoil granules. It is particularly prone to colonization by cladophora algae.
This bright green floating plant can also be anchored in the substrate or attached to wood or stone.