I think that The Smoke Monster
could be made up of "
Exotic Matter". Smokie could be the 'gasseus' form of Exotic Matter.
I say this because of the glyphs that were seen on the wall which led into Ben's secret tunnel..from whence he summond Smokie to maim Keamy and his men. Similar glyph markings were
also seen on a pillar in the "exotic matter" territory undeneath the orhid station.
This would make sense to me, since we know that hypothetically exotic matter creates a "casimir effect", which in turn has time and space properties. With this in mind, it could be argued that Smokie is able to 'time-travel' through peoples subconscious..as perhaps seen when it streamed memories from Eko's past in The 23rd Psalm.