79240
Because seashells are in some areas a readily available bulk source of calcium carbonate , shells such as oyster shells are sometimes used as soil conditioners in horticulture .
 oyster
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
Answer:
 oyster