These amulets possibly refer to the power of the senses1. The earliest are mostly bearded in stones and ivory1. They occur throughout all Dynastic Periods

Pink limestone
H 1.6, W 1.2, D 0.5
Late Old Kingdom-early
First Intermediate Period2
© The Trustees of the British
Museum #EA57812

Onyx broken with lost
encrusted eyes and mouth
H 2.8, W 2.8 Undated
© 2017 University College
London LDUCE-UC #38396

Green glaze H 2.8
W 2.0 Late Period
© 2017 University
College London
LDUCE-UC #38391

References

1Petrie W F M. Amulets, 1914, p. 9 and Figs. 1a,b
2Andrews C. Amulets of Ancient Egypt, 1994, Fig. 67d