Razor mussel- common
The razor mussel may only be a common beast. However, its powerful earth and water affinity allow for it to make extremely tough shells. They then use the water and the tough shells they condense to attack. Their razor edge is enough to cut and resist many things.
They can often trap stronger minerals within themselves and condense them in to smaller needles that they use to attack along with water. However, they have the ability to take over and breed in large areas.
This is not necessarily a bad thing. With this ability, comes the fact that they purify water as well. They can easily purify the strongest pollutants along with natural wastes. They are also a great food for larger beasts that can easily crack their shells and consume the insides.