ఆలుకాని ఆలు.
Explanation
The riddle plays on the homophone 'ఆలు' (potato) and 'ఆలు' (to think/ponder), meaning 'a potato that doesn't think'—the answer is 'వెలయాలు' (round gourd/pumpkin), which is round like a potato but empty/thoughtless inside, making it a clever riddle about something circular yet hollow.




