(ASAP!!!!!!!!!!!!!1)what are the symbols when Thorin and company are out the door

When they oped the door, "darkness flowed out like a vapour..." I'm thinking darkness as in don't keep going might be one. It is also silent when it opens though I'm not too sure what that might symbolize. Really there is hardly any description of the actual door. It's also small so it may even be meant for Hobbits and Dwarves. You can check it out at the end of Ch. 11.