Simplify the following text for a Grade 10 native English-speaking person.
Original: Lack of oxygen slowed bacterial decomposition and kept scavengers away , so leaves of palms , ferns and sycamores , some showing the insect damage they had sustained during their growth , were covered with fine-grained sediment and preserved .
Simplified: Lack of oxygen slowed bacterial decomposition and kept scavengers away . Leaves of palms , ferns and sycamores , some showing the insect damage got during their growth , were covered with fine-grained sediment and preserved .