I saw it long ago when I was a child, so bear with me.
It's a little old, approximate the early 90's
It's about people (aliens I think, in human form) being trapped inside concrete walls and floor, and being discovered decades later with sonar, and spiked out of the concrete.
They have been alive the whole time, and are still alive when released from the concrete.
They have pale skin, and I think there are 2 or 3 of them total.
Something about steel balls too. I think they are used to transfer conscience.
If this reminds anybody of a movie or TV show, be it new or old, any feedback would be appreciated.