Mysterious White Beads in Potted Plant Soil: Harmless Fungus

Question: Small (0.5-0.75mm) white bead-like structures spreading in potted plant soil for over a year. Hard, turn tan when rubbed, appear singly or in clusters with white fuzz. Resist drought. Plants healthy. What are they?

Diagnosis

Likely soil fungi forming mycelium balls during unfavorable conditions (drought/excess water). Most soil fungi are harmless to plants. Since plants are fine, ignore it. Soil fungicide might kill them, but unnecessary.