What Kind of Thing Am I?

I. I am essentially a thing of type T:

I survive from t1 to t2 if and only if a particular thing of type T survives from t1 to t2.

II. Psychological Approach

I am essentially a psychological entity:

I survive from t1 to t2 if and only if there is something at t2 that has certain psychological features because I had certain psychological features at t1.

Psychological features: Certain mental properties like beliefs, sensations, memories, etc.; and/or certain mental capacities like consciousness, reason, etc.

III. Biological Approach

I am essentially a biological entity:

I survive from t1 to t2 if and only if there is something at t2 that has certain biological features because I had certain biological features at t1.

Biological features: Life-sustaining functions like metabolism, circulation, digestion, etc.