183238
( However in several genera within a few families including the marine Naticidae and the terrestrial Pomatiidae , the operculum is primarily calcareous , in other words mostly made of calcium carbonate . )
 None
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 None