yes, actually this is one major advantage that snap has over many programming languages.
I have also a few posts about this, and I have a "ringless" custom block too. There are many ways to do it, as you can see.
I think basically the CommandBlockMorph is being told to render in the say bubble instead of a RingMorph, and a CommandBlockMorph is always able to be used as something that you can run or build on to make a bigger script. I'm probably wrong though.