Dear Jennifer,

This takes us away from Patrick's original question, but the parable of the turtle in the
ocean is very well known to Buddhist sources. In Praj~nākaramati's comments on
Bodhicaryāvatāra 1.4, for example, we read:

mahārṇavayugacchidrakūrmagrīvārpaṇopamā
"Like the turtle's neck that reaches the opening of a yoke in the great ocean..."

Buddhist sources understand yuga here literally as a yoke floating on a turbulent sea,
and interpret the metaphor to mean that it as difficult to obtain fortunate human birth as it is
for an old blind sea turtle to surface and by chance put his neck through a yoke
floating in the waves.