What tool of labor did the ancient people have to cleanse the fat from the inside of an animal?

Primitive people were engaged in hunting and gathering. The tool of labor with which they processed animal skins was a flake. It was obtained by breaking pebbles or other stones. The inside of the skin was scraped off with a flake to rid it of unnecessary parts. Then from the skin they made clothes, shoes, insulating elements for huts. The rest of the animals caught in the hunt went for processing. They were used to make needles, awls, various tools, spearheads and harpoons, arrows and ornaments.