The filaments are staggered and this is the type of muscle found in earthworms that can extend slowly or make rapid contractions.
ðə fˈɪləmənts ɑːɹ stˈæɡɚd ænd ðɪs ɪz ðə tˈaɪp ʌv mˈʌsəl fˈaʊnd ɪn ˈɜːθwɜːmz ðæt kæn ɛkstˈɛnd slˈoʊli ɔːɹ mˌeɪk ɹˈæpɪd kəntɹˈækʃənz.