I believe this is the start of a traditional origami Frog model which is where this base gets its name.
1) Start off by folding a Square Base.
2) Looking at the base from the top you’ll notice that there are four sort of arms.
3) We’re going to do a squash fold on each of these arms. Pick one…
4) …and squash fold it.
5) Flip the model over and squash fold the opposite flap.
6) There are two more flaps on the left and the right, pick one and squash fold it.
7) Once you’ve squash folded each of the flaps then you have the Frog Base.
8) If you open the model up you’ll notice these Mountain (black) and Valley (red) folds.