Dimensions help. It looks like an old fashioned dot roller, for roughing concrete but I've never seen one quite this small.

Yeah, could be the stair step version of the concrete dimpler.
Casey

Looks like a meat tenderizer to me

Calliope is correct. That is a concrete dot roller. Little hand jobs like that were pretty common actually. Typically used when doing the final floating/finishing of concrete. If you overdo the final floating, it tends to draw the cement to the surface and cause "neat cement" that peels off later, or leaves an un-uniform "glossy" spot on the surface. A hand dot roller or line roller comes in pretty handy to remix the surface cement and sand "on the fly" that may not necessarily require a full sized dot roller.

They were also used among potters I believe.

Well, gee- you could have at least left the photo up until the post left the first page...