Definition of THRUM
2: a hair, fiber, or threadlike leaf on a plant; also : a tuft or fringe of such structures
— thrum adjective
Origin of THRUM
Middle English, from Old English -thrum (in tungethrum ligament of the tongue); akin to Old High German drum fragment
First Known Use: 14th century
This shows what they look like inside. TOASTY. COZY. WARM. SOFT.
The little heart shapes are just "accidents" of how the un-spun tufts get incorporated into the vvvvvv's of the knitting.