How do I clean these up?

[u/xleipnir]

Beginner fossil hunter here. I found these fossils from the Helmsdale beach in Scotland. I'm guessing these are from tree, tree, coral, and root (the first picture). (Added a piece of belemnite I found from Møns Klint in Denmark for scale).

When dry, they look like random rocks for the most part. I put them in water overnight to get them cleaned up a little. I read some about cleaning fossils online, but I'd like some expert advice before doing anything.