Cave pearl pseudomorph?

[Mjq8]

Diameter 4.5cm at widest

Bought from street vendor in china who said its a “meatball” stone or 肉丸石(direct translation) 

i believe it is considered a cave pearl coated with aragonite? Other possibilities include lithothamnium fossil algae. Could anyone confirm ID? 

[ynot]

? could be a speleothem.

[rocket]

is it heavy? I have had lot of cave pearls a bit lighter than a normal rock, might be this is an indicator