Minecraft wiki entry for Cocoa_Beans, associated text: Cocoa pods have a different hitbox for each size, however the top is always 0.25 blocks below the top of the wood it is on.
If a cocoa pod grows while the player is standing next to it, the player is forced into the appropriate form of suffocation prevention depending on available space.
The pixels on top of the fully grown pod are 8/7 the size of those on the side.
Before they were made renewable, Cocoa Beans were considered rarer than diamonds.