A second function, in aquatic animals, is that gastroliths can be used for ballast to make diving easier.
ʌ WORD_BOUNDARY s ɛ k ə n d WORD_BOUNDARY f ʌ ŋ k ʃ ə n WORD_BOUNDARY ɪ n WORD_BOUNDARY ə k w æ t ɪ k WORD_BOUNDARY æ n ɪ m ə l z WORD_BOUNDARY ɪ z WORD_BOUNDARY ð æ t WORD_BOUNDARY ɡ æ s t ɹ ə l ɪ θ s WORD_BOUNDARY k æ n WORD_BOUNDARY b iː WORD_BOUNDARY j uː z d WORD_BOUNDARY f ɔ ɹ WORD_BOUNDARY b æ l ə s t WORD_BOUNDARY t ə WORD_BOUNDARY m eɪ k WORD_BOUNDARY d aɪ v ɪ ŋ WORD_BOUNDARY iː z i ə ɹ WORD_BOUNDARY