The spirit from the pond, Vodnik

The Vodnik is an aquatic creature, classified as a water spirit, of the genus theriomorph. Its physiognomy is very similar to that of a frog, with some differences.
These creatures are capable of developing both in water and on land, since their respiratory system, based on a complex network of blood vessels in the skin, allows them to easily oxygenate underwater, in addition to having two lungs to breathe on land. However, it is unknown if larval or pre-adult vodnik have gills to breathe, since everything indicates that they are.
Their limbs, unlike those of a frog, are much shorter, particularly the hind limbs, so it is a reflection of how clumsy and slow they can be on land, however their webbed legs allow them to swim easily through any type of aquatic environment. At the level of basic physiognomy, its muscular structure and bones do not differ much from those of a normal human.
Their eyes have a special membrane to be able to see underwater, as well as to be able to always be well hydrated on land, since they do not have eyelids to moisten them.
Their face has a lush green beard, made up of algae and other aquatic vegetation that they can use to hunt fish and other aquatic creatures that enter their hair.
They are not usually aggressive, however when they get angry they tend to destroy mills, dams or they can even drown people, so you have to be careful with them. However, being cold-blooded creatures, their moods will change a lot depending on the environment they are in.
They usually live in lakes, rivers or ponds, but always fresh water, they will never be seen on beaches or other coastal areas.