When the fertilized egg burrows into the uterine lining ?

Between four to six days after conception, the fertilized egg will develop into a blastocyst and burrow into the uterine lining, attaching itself firmly. In this early stage, the embryo develops a yolk sac, which provides its first nutrients.
I found on safari

Think it's rice because in many countries rice is the main food so it can be traditionally served all at once.