Robert Plant

Not as aggressive, but still pretty effective.

'I pick up kindling every where I go,' jokes Plant.

That would've sounded amazing.

Even the mud shark?

Four score and still going strong.

See which tracks the rock god loves most.

The singer recently found the letter that came at a pivotal point in his career.

Find out what makes both singers' voices so unique.

Even the best struggle sometimes.

Steve Birnbaum's Instagram is a gift to music fans.