Every few months scientists pry them up and measure the amount of pollution in their shells to see if chemicals discharged into the sea are harming marine life.
Iga paari kuu tagant tõmbavad teadlased need karbid üles ja mõõdavad nende kodade saastetaset, et näha, kas merre lastud kemikaalid kahjustavad mereelustikku.