There is much on the Internet and other sources about this.
The host turned into a piece of flesh at or after consecration around 8th century A.D. It remains so until today.
In 1970, tests were conducted on it with these results:
It is indeed human flesh.
It does contain within it human blood.
It is muscle tissue.
It is tissue from a human heart!
Most Sacred Heart of Jesus, I trust in You!
Most Sacred Heart of Jesus, I love you!
Most Sacred Heart of Jesus, make my heart like Your Heart!