When they occur out of their localities, hypothesizing a transport mechanism is usually possible, such as the hulls of ships.
wˌɛn ðeɪ əkˈɜːɹ ˌaʊɾəv ðɛɹ loʊkˈælᵻɾiz, haɪpˈɑːθəsˌaɪzɪŋ ɐ tɹˈænspoːɹt mˈɛkənˌɪzəm ɪz jˈuːʒuːəli pˈɑːsᵻbəl, sˈʌtʃ ɐz ðə hˈʌlz ʌv ʃˈɪps.