What is this small ceramic piece?

[Bungalove]

We call the back yard of our 1916 house "The Giving Yard." Things are constantly working their way up through the grass and soil, or we find things as we clean and remodel. For example, a 1939 British two-shilling piece, and we're in Montana. ???

Anyway, out by a very old shed that we're fixing up, my husband found this thing while tearing out a recently added slab of cement. It was underneath. It's white ceramic, approximately 3-1/2" long by 3/4" wide. One side has a recessed rectangle with a diamond shape in the middle and the opposite side has three grooved channels. There are two holes for, I assume, screws or nails.

I think it might be some kind of old insulator for knob-and-tube wiring but am not sure. Thanks!

[Gothichome]

Bungalove, I believe your correct.

[Mick_VT]

+1 I believe its specific use was to support runs of pairs or three wires with close clearance or surface mounted e.g. across a ceiling the wires would be gripped clamp like between the two halves, the whole thing being held together and affixed at the same time by two screws through the holes.

[Bungalove]

Thank you very much!