Rotate object around other object center in Inkscape

I had do design a simple scheme of a cell with certain markers expressed on its surface. The idea is pretty straightforward: draw a circle for the cells and draw a rectangle for the protein. But what if I want to change its position, by rotating it around the circle center?

Well, first draw the objects… Then, click buttons: Snap other points, Snap centers of objects and Snap an item's rotational center:

Select them both, then double click on the red rectangle so its rotational center becomes visible. Drag it to the center of the blue circle and it will snap there. Then, the red rectangle can be rotated around the circle:

That’s it!