Simplify the following text for a Grade 11 native English-speaking person.
Original: 29 Amphitrite is one of the biggest S-type asteroids , probably third in diameter after Eunomia and Juno , although Iris and Herculina are similar in size .
Simplified: 29 Amphitrite ( , or as in ) is one of the largest S-type asteroids , probably third in diameter after Eunomia and Juno , although Iris and Herculina are similar in size .