SB 11.15.10
bhuta-suksmatmani mayi
tan-matram dharayen manah
animanam avapnoti
tan-matropasako mama
Translation:
One who worships Me in My atomic form pervading all subtle elements, fixing his mind on that alone, obtains the mystic perfection called anima.
Purport:
Anima refers to the mystic ability to make oneself smaller than the smallest and thus able to enter within anything. The Supreme Personality of Godhead is within the atoms and atomic particles, and one who perfectly fixes his mind in that subtle atomic form of the Lord acquires the mystic potency called anima, by which one can enter within even the most dense matter such as stone.