I have started experiencing recent heartburn, chest pain, and a palpable marble-like knot near the hiatus, below the zyphoid process. can hernias be hard like a marble?

Hiatal hernia can't : Be palpated. What you were feeling is i believe, still part of the xiphoid, the tip of it. Your chest pain is likely from acid reflux. Get reassurance from your dr that your heart is a ok! take care!

Several,items: The hiatal area is considered deep at the esophageal area as passes from chest to abdomen. The lower end of the sternum is the xiphoid and can feel lie a mobile or fixed marble in place. A hernia can become firm with entrapped fat. Need full history and exam to make a diagnosis.

Not usually: If it's painless and permanent, it needs attention. If it hurts, it needs attention. If it's painless and temporary, you may just be feeling a muscle spasm or, if you're really thin, your colon. You can't feel a hiatal hernia - it's a radiographic or egd diagnosis.

Hernias are soft: Hernias in the central abdominal wall, including the belly button, can start small but they are soft and generally can be pushed back in. It must be something else. Sometimes the tip of the xiphoid bone points up and could feel like a knot in the upper abdomen. Why not let the doctor feel it if you are still concerned.