Field Found Fossils from East Sussex

I'm new to the forum so I thought i'd have a try at posting a few of my better fossils found in the fields beneath the scarp slope of the south downs in East Sussex. In the past i usually gave them away but since a visit to the Isle of Wight I found i'd like to know more about what I have found.
I know very little about them so any help with identification would be gratefully recieved.

1 & 2.
These are a common find here, though its rare to get them without plough or frost damage





3.
I believe this is an ammonite formed from marcasite,

.

4
Another shell formed from a material similar to Marcsite without the crystaline appearance that Marcasite usually has.





5
These large ammonites have turned up in the past when the plough has gone a bit deeper than usual. Unfortunately this one has been out in the frost for a number of years,




Thanks for looking.

Rob

They look great! The first two are Echinoids (sea urchins), and 4 is a brachiopod. (I couldn't be any more specific I'm afraid, there's thousands of species of each!)

Nice finds my friend