What's the name of these parts when importing animated models?

When you import an animated model, it appears with an arrow icon which allows to expand and see all parts of the imported model. I can distinguish the meshes, the avatar, the animation clips, but there's another element which has a Transform component on it and I don't know the name of it. It is the selected element in the following capture:



There seems to be at least one per mesh in the model, and its purpose appears to be to define the relative transform of the mesh on the GameObject, but I couldn't find information on the Animation documention. What's the name of this element?

Thank you in advance.

 

Could be a null object from the originating 3D app. Like a spline curve rig controller. Open the file up in your 3d tool to confirm.