It’s been ages since I touched a vector art program but wouldn’t a simple “select the bit you want then copy and paste into a new document” work for this? Or do you want to keep the whole group intact and just edit bits of it?
Sorry if Illustrator doesn’t work that way, like I said… Been a while.
It’s possible that they’re part of a compound path. Try ‘Release Compound Path’ in the Object menu.
You could look in the Layers palette and expand the list until you see individual items. That often gives you a clue.
Failing that, use the white arrow to drag select the items you need and copy / paste to a new document, as Rodak said.
Alt way - double click into the image you want - it isolates it in the compound path, then you can select it and cut it - exit the isolation mode and paste it to the artboard.