? Fossils

[Den]

Could anyone tell me if these are fossils at all? I work in a school and the children are very interested in them. If they aren’t , I am also interested in what they actually are, so I can pass on any information to them. Many thanks! 

[TqB]

They're four different types of fossil sponge in Upper Cretaceous flint.

Sponge ID is tricky and really needs a specialist but:

no. 1 could be a piece of Ventriculites or similar,  no. 3 looks like Porosphaera and no. 4 could be the branching Doryderma (aka Brochodora).
 

[Den]

That’s much appreciated, thank you! 

[Coco]

The 2 reminds me of an Echinocorys sea urchin seen on the side, and in an internal mould, so no more identifiable.

 

Coco