Simplify the following text for a Grade 11 native English-speaking person.
Original: Her observations played a key role in the discoveries that belemnite fossils contained fossilized ink sacs , and that coprolites , known as bezoar stones at the time , were fossilized faeces .
Simplified: Her observations played a key role in the discoveries that belemnite fossils contained fossilised ink sacs , and that coprolites , known as bezoar stones at the time , were fossilised faeces .