X's mean that they got sold/ran away.
You can see how the names correlate! Kumbu, Zumbu, Kundru, Dundru, and Zundru all end with a U. The orange cats are named with K as the starting, (Kumbu, Kundru) The white & black cats are named with Z as the starting, (Zumbu, Zundru) Dundru, well... hes mostly white, so hes special. Fun fact: I named them all XD
