Cut the boiled octopus into bite-sized pieces.

Slice the lemon into thin half-moon shapes and squeeze the remaining lemon for juice. Cut the cherry tomatoes in half.

Mix the olive oil, salt, and pepper in a bowl. Add the lemon juice, octopus, and cherry tomatoes, then mix well. Chill in the refrigerator.

Boil water in a pot, add salt, and cook the spaghetti according to package instructions. Drain and rinse under cold water, then drain again.