Simplify the following text for a Grade 9 native English-speaking person.
Original: The heterokonts or stramenopiles are a major line of eukaryotes currently containing more than 100,000 known species , most of them diatoms .
Simplified: The heterokonts or stramenopiles are a major line of eukaryotes with more than 100,000 known species , most of them diatoms .