I have metal square tool to make kinda woolen crochet squares, what's it called?

This "tool" was popular in the 70's for making ponchos and blankets. The finished product looks like it has been crocheted. There are many different patterns that can be used and i'd love to find some but without knowing what it's called it's impossible to find any. The tool is a metal square, flat on one side, on the other side there are four pieces of metal that slide out that have kinda like little fingers along the outside edge, which is where the wool is looped around. Please help.