Keep track of elements inside STL vector
I would like to know what is the best way (if there is one) to keep track of an element inside an STL vector.
Consider I have some big object 3D models, that take up a lot of space each, alligned into an STL vector and each of those models may have one or more smaller elements that refer to this model, holding proprieties such as mass, position, orientation and so on.
How do I make sure the smaller propriety elements always have a valid reference/pointer/index to a model in the models vector? Is iteration through the vector, looking for a specific marker always necessary?