Core of tomatoes

Question

Our tomatoes often have core-like color and substance going down at least 1/3 of the tomato. Usually there is some yellowish/orangish color on outside of where it is and feels very hard to the touch.

Answer 1

This sounds like a normal tomato description.
The core of the tomato is directly under the tomato stem.
Here is a link with more information.

http://www-plb.ucdavis.edu/labs/rost/tomato/Reproductive/anat.html