Its meant to be fibrous cotton lol (used as wicking material for the e-liquid). I modeled a base shape first, split it down the middle for greater control of each half, then scattered two tiny fibres (splines with minor thickness) using corona scatter over the surface of the shapes, then hid the base shape from the viewport.
The first scatter was offset in the z axis to give the cotton density/mass to fill out the shape, then a 2nd scatter was applied with only a minor z offset to get the wispy edges. Both scatters have tweaked rotation and scaling so that the fibers look like they are flowing in one direction, but still slightly random. It's just a simple white material with low levels of translucency applied.
