Of course, a shower of debris fell out at the same time - somewhat to my surprise as it hadn't looked dirty. Most of this landed on the top of the ladder and when I went to clean it up, while Pisces was taking our visitor outside, I was deeply saddened to find six tiny desiccated skink corpses. There was a dead spider, too, that had built a scraggy web up the side of the tube before it succumbed.
The thing is I hadn't even realised anything could get into the tube until I saw this little skink and I'm still not sure where or how they are getting in. The tubes are supposed to be sealed to stop dust getting in and there was hardly any dust in it but there has to be a opening somewhere - and to let in a skink of the size of this one, it isn't going to be minute. I looked up into the tube but couldn't see anything so I guess the next step is to get someone younger and fitter than Pisces and me to go up on the roof and check the seal.
In the meantime, I'll be checking for unexpected visitors regularly.