Board Thread:General Discussion/@comment-26980570-20160320192450/@comment-26980570-20160925173243

The answers of your questions are pretty easy to answer @Alkhor-dm Many monster till this date are alive...they also saw the surface...So normally someone might have illustrated what the surface looked like in one of their book...sans is very knowledgeable due to this whereas Paps doesn't even know what Labradory (Labrotary) means. We don't exactly know when the skele-bros saw the outside of their cages so It very well could be that Toriel went to ruins befor skelebros came out.

Easy. Both the skeletons were in the shed/basement of sans's house (please read my theory before asking these questions)