 So for the alpha helix in particular, if I just draw it this way, it might look like a collection of atoms. But we could of course look at this as a surface representation. And look at the surface representation, you kind of, there's kind of like some edges and valleys here, right? We can draw some lines here roughly along the edges, or you can take the same atoms but draw lines in the other direction. And it's not, maybe it's not so much the edges here, but the rifts between the edges. So what if I take another copy of that helix and now try to put them on top of each other? It would be kind of neat to pack the edges against the rifts, right? What that is going to lead to is that if I take a structure like this, there are edges either in roughly 25 degrees or minus 45 degrees, or minus 25 and plus 45 degrees. If I then take a second helix and I'm going to pack them, there is no way I can pack them like that efficiently. Because that would mean that I would have clashes between these edges. It would be empty space. But what if I take them and rotate just a bit? This again does not look good. But if you look at the very crossing point here, then I could have the edges and the valleys fit perfectly to each other. We see that in real protein structures. So in this particular case, it's hemoglobin. We'll get back to what the Siem group does. Actually, sorry, this is myoglobin I think. It's binding oxygen in your muscles, if it's myoglobin. And you see that all these helices, they appear to be thrown in almost randomly. But these crossing angles fulfill these conditions where they cross to make sure that the ridges and the valleys fit with each other. Which again, we're in this hierarchical structure building. And instead of having amino acids and building secondary structures, we're now taking stable secondary structures and using those to build larger components. In theory, you could call that tertiary structure, but we haven't really formed an entire protein yet. So sometimes when we talk about collections or a few secondary structure elements, we tend to use the name super secondary structure. And you might see that in a few cases. So think of super secondary structure as common elements involving more than one secondary structure element, but it's not quite yet a full protein.