The teasers were...

As guessed, Wotisit one was a plant.. or what was left of it. An old Ivy [Hedera sp.] trunk and here it is...

You just have to ask...
Is the wall holding the ivy up?
or...
Is the ivy holding up the wall?

Number two was a section of a very small, but pretty snail [so close Susan... 'twas a mollusc] and isn't it pretty?....

In a whorl of its own! [Only 8mm across!]

Number three was the abdomen of a fabulous "garden"  or Orb Web spider Araneus diadematus

This is the 'view' of the back of the abdomen.

And this is it from the front!

I hope that the arachniphobes out there have picked themselves up!!

Wotisit Four was the thorax, as Susan guessed, the 'giant' hoverfly Melissa crabroformis

I love the "tribal mask" that the pattern on the thorax makes!