Caltiki il mostro immortale

I saw this when I was 8 years old, and it scared me so much I had to momentarily leave my seat. I ran back to the men's restroom and hid inside for a minute or so, then slowly came back out and stood in back by the usher and watched for another minute or two more, and finally returned to my seat for the rest of the movie. This never happened to me in any other movie, and as an adult, I was very curious to know just what it was in this otherwise standard black and white B-Movie Monster fare that could cause such a reaction. I just watched it again, for the first time since 1959, and I believe it was a combination of having my wits scared out of me when I identified with the little girl and her mother trapped in the bedroom with Catiki swelling up against the door, and stomach churning revulsion at the nasty looking mess that was left after Caltiki started digesting its victims. Unlike Steve McQueen's Blob which looked almost like an edible piece of cherry Jello, Caltiki sometimes took on the appearance of a soiled cloth rag completely saturated with thick dark mud (or some unmentionable organic substance), and the mess that was left after it digested its victims was indescribably disgusting for the era. The plot is corny and hackneyed, with the obligatory hysteria over the evils of radiation, and knuckle-headed careless scientists. But it is campy and scary, and worth watching. I ended up springing for a DVD, since I never see this shown on television anymore, apart from once seeing it offered by Showtime many years ago. Why do movies like this just vanish?