First, is the titan really inside of the wall like being trapped in it or just doing his/its job (lol)? I thought it was on the other side ever since because I have seen many comments/texts using the word "inside" which is very confusing.
Also it was said so far in the anime (currently S2 E6), that walls are (possibly?) made of titans' "crystals" making it pretty much indestructible, so doesn't that mean that titans aren't neccessarily inside of the walls since it would make the plot point a very funny one.
I am also confused as to how the walls are said to be "indestructible" like titans' crystals except certain parts like "entrances/exits", but some titans are seen to be able to pretty much destroy wall parts that are said to be indestructible like how (the collosal titan destroyed some parts of it) not sure if it really did though?
P.S. It's okay to spoil about the origin of the walls in your answers.