Why Was Rick Afraid of the Cob Planet?

Although the Smith family considers the cob planet pretty cool, Rick finds it terrifying and freaks out when he closely inspects the cob-based items because he discovers everything is on a cob down to a molecular level. He freaks out noticing it because cob atoms could take over the human body and transform them into the cob. Different atom particles mess with biological receptors and have an effect similar to radiation poisoning or neurological disorder.