In ancient Egypt the heart was surprisingly assigned the role of the brain and was the seat of intelligence1. This highly common amulet with lugs was made in faience, (semi-precious)stones, glass, bronze, gold, etc. Position on mummies: upper torso1. Mainly from the New Kingdom onwards1

Glass H 2.1
New Kingdom
Dynasty 18
© The Trustees
of the British
Museum
#EA 29265

Stone flat back topped by a jackal/dog head
H 3.8, W 2.8, D 1.7 New Kingdom © 2014 Musée
du Louvre/Christian
Décamps #E 11682

Incised green jasper
H 5.2 New Kingdom
Dynasty 18-19
© The Trustees of
the British Museum
#EA 15619

References

1Andrews C. Amulets of ancient Egypt, 1994, pp. 72-73