Never in my life had I thought of vagina dentate and the salt vampire. Its mouth looks like it, though. Is that your own thought or are there others who have said they think/see that?
Giving that one some thought. And looking for a screen cap of the other, just for curiosity.
I don't remember seeing it anywhere else, it's just something that occurred to me as I was mulling over some of this stuff in retrospect.
Maybe it wasn't written that way on a very conscious level, but the salt creature is actually analogous to the idea of a succubus. For obvious reasons in-episode references to anything sexual were very very indirect. But they were definitely there if you want to look for them.
For example, the salt creature is living on the planet alone with that surviving male scientist (whose wife the salt creature killed) for years before the Enterprise visits. I believe there's dialog that says the salt creature fulfills his "needs." (In exchange for the salt tablets I guess?)
The salt creature replaced the scientist's wife. The salt creature looks into people's minds and creates their "fantasy." It's always highly sexualized even when the salt creature did to to Uhura, instead of a sexy fantasy woman, it became a studly male crewman.
When Chekov sees it, it's another sexy image of a woman that Chekov knew, and I think they even play "sexy" music in the score.
So, that's what a succubus is, except succubi are supernatural, but psychologically it's the same thing. The succubus comes at nighttime, has sex with their victim, and basically sucks out the victim's life force.
Now the way it's explicitly depicted when the salt creature attacks it creates great pain but why wouldn't the salt creature be able to delude the victim into thinking they were having sex with the fantasy person? Obviously on T.V. they can't show the salt creature giving its victims orgasms while sucking the life out of them. So it can't be a perfect parallel.
If you remember the Tobe Hooper movie "Life Force" from the 1980's (which also had Patrick Stewart in his pre-TNG days playing a supporting role), based on a Colin Wilson novel, it's about "space vampires" that come to earth, in the form of very physically attractive humanoids. Their real form is like a gian bat like creature though. When they get physically close to a human they suck the "life force" out of the human which is depicted as electrical sparks.
It's pretty much the same idea.