Jessica Biel says motherhood is the "most challenging job in the world".

She shared: "It's sometimes hard to find the words [to describe motherhood]. So amazing. So lovely. I'm over the moon. Honestly, I would say motherhood [is the most difficult role I've done]. It's probably the most challenging job in the world, but also the most joyous."

But Jessica is thankful for the support of her 'SexyBack' singer spouse.

She added: "Justin is a funny, sweet and caring dad - everything and more. I'd call him the perfect parenting partner."

And the 34-year-old actress has described her son's smile as "pure magic".

When asked what is her favourite time of day with Silas, she told Britain's OK! magazine: "If I had to pick one it would be when he's waking up from his nap. He looks up and sighs and I can feel his smile from deep inside. That feels like pure magic."

Meanwhile, Jessica previously praised her husband Justin for being a "wonderful partner".

She said: "Well, he supports everything that I do and that's why I think he's a wonderful partner. And we should just be able to talk and laugh and learn together."

And the 'Blade Trinity' beauty is reportedly considering having another child with the 'Can't Stop The Feeling' hitmaker.

A source said: "They're already thinking about having more kids. They are homebodies. Justin is so happy. He's had career success, and now he says family is the most important thing."