DustyStyx: This
walkthrough says it should be behind a set of wooden doors:
Level 3: Temple of Poon
CABALCO INDUSTRIES
...
After defeating the Death Shroud, jump into the water in the altar. Pick up the Necroward and the Life Seed and jump back out. Exit through the door and make you way around to the stairs. Climb down them and walk around (enter one of the two large wooden doors to pick up the Life Leech) and go up the stairs. Walk forward until you get to a fork in the passage. You can pick some Howitzer shells up to your left, then take the passage to your right. Cross the bridge, and after it collapses on you, jump up into the cave. Find the lift and ride it up. Follow the passage around (smashing the boxes as you go) to another lift. Ride it up to end the level.
DustyStyx: Already past that point :( Must have missed it because of full weapons, I don't usually miss any doors. I'll see if I have a save and check it out, but I'm not replaying all the way from there. And the walkthrough doesn't mention any others :(
