Possible Clues:

• Cephalopod mollusc
• Captain Nemo's submarine
• Captain Nemo's sub
• Small sea creature
• Shell to arrange aunt to go to Illinois with you and me
• Usual tin for a small sea creature
• Nemo's submarine (Verne)
• Vessel in 'Twenty Thousand Leagues Under the Sea'
• Nuclear submarine
• Cephalopod with a spiral shell