In the the later 1950's I read a story in one of the cheap SF magazines which were around then. The story featured an alien artefact that looked like a smooth curved stone or pebble. In the story it was picked up and the human inclination was to stroke it, and its feeling was so good that it entranced or hypnotised the human who then became a victim in some way.
It was as if it was a pacifier for adult humans which they could not resist.
Any ideas about what the story was called and when, and where it was published? I was only a young kid then and used to swap magazines with friends.