Thread-like

IGM is a network or web of thread-like formations of diffuse gases left over from the Big Bang that links all the galaxies in the universe together.

Source: tatoeba (11114582)

The Erysipheae are typical epiphytes, which weave a mycelium over the surface of plants they attack; the mycelium retains its hold by adhesion-discs or appressoria, and from certain parts of these a fine thread-like process is given off, which, after piercing the epidermal wall of the host, swells inside to a simple or branched sac, the haustorium.

Source: wiktionary