So I found a new place where the members of the Algae Liberation Force were training for an invasion. I have an in-wall ladder and corner stairs. Around the edges there is a rail that is screwed to them to hold the liner in place and seal around them. The rails have a little C channel that covers the screws. I thought to pull one of the covers off, and it turns out there were algae insurgents gathering and training behind all of them. So I took executive action and sent in the special cleaning forces to eliminate the threat.