Thank you to Karin for reminding me that it is the Jacob's Ladder stitch that I was thinking of previously. It resembles the Cable Loops from The Complete Photo Guide to Crochet in that you draw the upper loop through the lower loop to complete the work. In the "regular" Jacob's Ladder afghan you work the chains and then skip the same number of chains. In this pattern you do not skip chains. I think it would be easier to plan ahead for size in this one as in the skip chain version your project becomes smaller as you pull up the loops.
Here is how to work the Cable Loops. I am not going over the entire pattern. Just the method of pulling the loops through. It is fairly easy once you know it, but it is the sort of thing where I think seeing is easier. If the pictures don't clear it up for you, just hop on over to YouTube and you will find tutorials on working Jacob's Ladder. Even though this won't be exactly the same as this stitch, it will show you the method of drawing through.
So here we go. You start at the bottom of your square. Pull the second loop from the bottom through the last loop from the bottom (going through the back of the loop) as shown. You can use your crochet hook to do this if you want. I chose to use my fingers.
I know I should have used solid colored yarn here so you could see it better, but this is what I grabbed without thinking of taking pictures of it.
Then grab the loop you just pulled through and sit it up a bit. You will draw the next loop up through that one you just pulled through. IOW You will grab the third loop from the bottom and push it under and through the second loop from the bottom.
You will continue like this to the last loop.
If you are working each column of loops and finishing them as you go, then at this point you will have done all the previous ones. You will have worked single crochets along the row, grabbing the loops, to this point. If you are NOT doing them as you go, but prefer to do all the loop work first, then you will need to put a stitch holder in the last loop to keep it from undoing.
Insert your hook through the middle of that last loop.
Yarn over and pull through. You will have two loops on hook.
Yarn over and pull through both loops. You have completed a single crochet and attached the loop to your row as well.
This is a very nice looking square. I worked a couple of extra rows of single crochet at the end. If I made another I would do only one row of single crochet at the bottom. That is because I prefer the same look at the top and bottom.
If you want a more "compact" look, you can do just one row between your loops and make shorter loops, or fatter loops if you keep them the same size. I think I prefer Margaret's version, but here is an example of a square worked with one row between, with loops of same size. I don't know if you can see the difference in the photo.
This stitch is classified as easy and it really is once you get the hang of it.
Just fyi, I used a chain of 21 for my square. Mine came out about 5 3/4" without a border around it.
This was a fun square to do. Not so challenging as to be frustrating, but not so simple as to be boring.
If you want to also try the Jacob's Ladder, you can find a pattern at Bev's Country Cottage, and another at Beth Ham's site, a Trunk Full o' Fun. Beth notes that your afghan will end up about half the width of your chain so you see what I mean about judging the finished size of your project using that stitch. As I said before, the Cable Loops does not work that way. The finished size should be very close to the size of your chain since you are not skipping chains.