The spines of Eriosyce matancillensis are long, slender, and contorted, with a gray-brown hue, growing upward. Their dense arrangement entirely obscures the plant's stem, making it look like a tangled mass of dry grass.

GM1854 is thought to be a natural hybrid (Neoporteria matancillensis × Horridocactus limariensis), displaying darker and more robust central spines than the typical form.