Occupied!

Homo sapiens is not the only species to exploit and colonize. Here are two examples I found on a short walk. 
On the right is a cherry gall attached to a scrub oak leaf along the lane. The oak has formed the ball out of its own substance to house a wasp larva in response to an attack from its parent. The mottled markings on the gall probably indicate air sacs which deter the invasion of another species seeking to make use of the spherical nursery for its own eggs -  even galls are subject to invasion.
 The gall will turn bright red like this before it drops off, job done..

Left: on the coast I noticed that some seed heads of tall grass had been  requisitioned  by spiders (possibly the Grass Head Spider Cheiracanthium erraticum although I have yet to find it - but watch this space.) I was intrigued to see how  the silk strands have been used as guy ropes to bend the seed head into a curve in order to form to a nest. I wonder if this gave our ancestors the idea for doing the same sort of thing with  vines and creepers and eventually to invent 'webbing'.