What is this ugly beast

[Chengjing]

Found this on a beach East of England, it looks like a stone been blown up from inside. There is a hole inside. Does anyone know what it is? Thanks

 

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[fuss]

Looks kinda like some stuff we have here that I find in Lake Michigan. It's probably Some kind of carbonate thing that may not have a specific name with vugs possibly filled with quartz or calcite crystals. Try a drop of muratic/hcl acid and check for a reaction.

 

[Chengjing]

It does look there is thin layer of crystals inside. Thanks.