Virtual Villagers Tips & Tricks, Walkthroughs, Guides, Hints and HelpLast Day of Work Official Forums: Virtual Families, Virtual Villagers, Fish Tycoon
That box increases the maximum population for your tribe by 5. So, as you observed, you can now have 31 living villagers (5 more than the previous limit). Even though it sits on the mausoleum, it doesn't affect the mausoleum's capacity.