Hi. I've never seen a need to ask this question until now, can creatures/objects have different elements? For example, your Athame be earth or a Water Dragon be fire? [having a minor argument with someone and I need clarification]
Traditionally, a living creature is somewhat composed of all of the elements. Water is the blood, the life essence, the glue that holds it all together. Earth gives it substance, makes it solid. Air the vapor it breaths, its thought, etc. Fire, the warmth of life.
In candle magick people use a green candle to represent earth and money so you in my mind can transfer this method over to anything. What I mean is what's preventing me from saying the pond nearby is on the earth, in the earth, so to me it represents earth. In magick tools are often used to aid in visualization and mental works such as how a athame is used to direct energy, even though you could simply do so with your hand. In this instance element categorizing is used to help your mind, so if your the one doing the magick you should be able to call something whatever element it seems to you as it is more a state of mind and will. This is just my opinion.