Hi, I'm 31 Weeks Pregnant And I Started Eating Eating

Hi, I'm 31 weeks pregnant and I started eating eating slate pencils from last 3 days, I almost ate one full packet. Does it infect me and my baby? I'm very much tensed and couldn't control stopping those things from eating. Please give me suggestions. My husband says that eating slate pencils during pregnancy produces worms in the womb, is that true?? Am I doing bad for my baby??