Metal Adornment at Building Entrance in Eixample Quarter, Barcelona

Walking along Eixample streets it is not rare to find curious metal adornments like this, guarding the entrance of modernist houses. I am not sure about the real purpose of such figures but it is obvious it wasn't purely aesthetical. One of my theories is that between the door and this mythological creature, you could easily slide a wooden board to protect the house against flooding. This was usual practice in Barcelona not so long ago. Nevertheless I am not sure about this and maybe some of you may think of another use.