The final normal star for Shifting Sand Land will have you going back inside the pyramid. In fact, once you get back inside, return to the very top of the pyramid, but don’t grab the star up there. You probably saw a little platform sticking out from near the top of the pyramid, right next to the sand waterfall. Drop/jump down to it and you should see a familiar red number pop up, meaning you found a secret. There are five of these secrets inside the pyramid, all located fairly close to one another.
From the ledge with the first one described above, you will want to jump down and land on the ledge side of the sand waterfall (when facing it). If done right, you will land on another platform, triggering the second secret. Jump down and back to the right side of the sand waterfall for a third platform, and secret. You should now be right above the flowing sand river, so drop down to it and follow it, making sure to keep Mario’s head above ground. The two lone coins on this flowing sand will be the final two secrets, with the star spawning at the very end.