Matsya Purana 180.18

180.18

valmīkena samākrānto bhakṣyamāṇaḥ pipīlikaiḥ.
vajrasūcīmukhaistīkṣṇaiḥ vidhyamānastathaiva ca .. 180.18 ..

By continuing his austerities like that, for one thousand divine years he was surrounded by ant hills on all sides White ants and insects began to feast on him After sometime all the flesh and blood were almost consumed, and that devotee of Śiva with his bones, began to shine like a white shell—17-19