Though Sebastian was not able to explore the full catacomb during his previous visit, the only hall where he entered and battled before escaping was enough of a reference for him to guess the overall layout of the huge mausoleum.
In his opinion, this catacomb's structure was a huge network of underground tunnels and passages that led to other halls like the one he was in currently.
And just like this hall, he guessed that the rest were filled with piles of skeletons. The reason for this was what he didn't know.
All he knew was that the dangerous experiment that was done by the Atlantian Professors was probably related to skeletons in some way or the other.
Probably, the owners of the skeletons were test subjects who exhausted their living time and were discarded, or the skeletons may be a crucial ingredient that they needed to make their experiments a success.
Whichever of these theories was true, Sebastian was not sure.