General_Gigan

Chosen answer: This has been answered before. The liquid, which is apparently a mixture containing human blood, is a defoliant that destroys Earth's foliage and replaces it with alien vegetation.

raywest ★

Answer: If you're referring to the liquid that pours out at the end when the alien piloting the tripod that was shot down dies, it may stand to reason that since the tripods themselves are built the same as the aliens (three legs and the same shaped head) it's a type of liquid that allows them to neurologically connect to the tripods and control it as though it's a dream. Sort of Pacific Rim-esque except no suit is needed.

General_Gigan

Answer: I believe that this orange liquid has nothing to do with the red weed or something like this. As this liquid is only visible when tripods are being attacked from inside or seriously damaged, this may hint that it is blood from the creatures or some kind of liquid flooding the whole habitable spaces inside the tripod, as the creatures look a little amphibious. Both theories fit the fact that in the last scenes, the liquid comes from the same door the alien puts his arm out.