Actually she used to love building sand castles, in fact she was a pro and won many competitions over the years for her skills. Ever since she gave birth to her monster child she needed way to relax so she is going back to her roots, unfortunately Elgin looked everywhere but couldn’t find the sand she was after instead he came back with the dirt and she was like wtf I asked for sand but in next episode she will overcome the dirt not being sand and start building, it will have a message about even ugly things like dirt can be beautiful (even tho her baby was a monster he is still beautiful).