Ribbon, as three marks
Amit picked Ribbon out of the six. These are Build, Buy and Back drawn in that language, generated against the chosen image so the stroke weight and the way the band turns carry over, then traced to vector so they are real files rather than pictures of files.
Build
Rises from one point and turns once to show its edge. It has a beginning, which the other two deliberately do not.
Buy
Two ribbons that start apart and become one band at the top. They share the ending, not the beginning.
Back
One ribbon arcing over a smaller flame it never touches. The larger form is not the fire.
One correction
I told Amit these had to survive 22px. They do not ship at 22px: the marks sit at 38 on the homepage, and 22 is the size of the small plus buttons, which are a different element. 22 is shown above anyway, as a stress test rather than a requirement. At 38 the ribbon holds; at 22 it thins, and if it ever needs to live that small the weight is a parameter in the trace.
Before the trace
The raster the vector came from, in case the trace lost something worth keeping. Tracing tightens the curves slightly and drops the finest taper at the tips.
Say ship it and these replace the three marks on asfiro.com. If Build and
Buy read too alike at a glance, that is the one thing I would change first: they are both
upright twisting forms, and Back is the only one with a distinct silhouette.
Still open: the chambered spiral. Four candidates are on v2 and none is chosen.