The best suited punctuation for non-restrictive clauses are commas. The information of the clause can include surprising information.
Examples:
- My cat, which loves some vegetables, takes the vegetables from my shopping bag.
2-My teacher, who has tatoes on his bald head, loves teaching arts.
3- My teacher , who looks very young, is very traditional.
The underlined clauses are examples of non- restrictive clauses. They are between commas because we can omit them. If we take them out, the main clauses have meaning, anyway. The information in the non-restrictive clauses can be surprising- look at examples 1 and 2 above -, or not -look at example 3.