Originally Posted by SnapDragon
I wasn't keeping careful track when I got them, but FYI I believe the extenders (4 energy, 4 life) are on levels 2, 4, 6, 8, 9, 12, 14, 15. They don't require a second playthrough; I think they're all obtainable with the aliens you have at that point in the story.
Here's what i have (even though you have it already) but for others a list i was making while looking for the remaining ones. I don't recall 9, so that may be wrong and 13 and 14 i didnt keep track where they were. 13 and 14 may be 14 and 15. confusion, I know.
Stage 2 - After walking through Red Door - go right and across the hot beds. In the upper right of the "room"
Stage 6 - Above the red keycard. Must transform into Dinosaur dude.
Stage 7 - When you reach a yellow energy bar on a ledge with spikes near it, go down the ladder and jump across to the ledge, youll come to a skull magnet descend down the ledge it is about 3/4 down and in the middle.
Stage 9 - There is a moving platform section (2). It is on the bottom floor of the second section.