Mystery fossil / interesting rock?

[John.E.K]

Found this rock in Charmouth beach (south west coast of England) a few months ago. The period is early Jurassic and is generally dated to ~ 190m years ago. 

 

I have soaked the rock rock in vinegar solution and gently scrubbed it with a soft toothbrush. I can see the small crustacean imprint in the middle, but I am curious RE the pattern on the top portion and grey rock in the middle. There is nothing on the reverse/I haven't been able to expose anything. 

 

Please let me know if you see anything interesting or if it’s just a rock! 

Thanks,

J

[caldigger]

Are there no clues on the other side?  It does seem to be something, but I am not versed on critters from UK waters to be of any help.