Prince's trippy "Cosmic Day" is the latest tease for the super-deluxe reissue of his "Sign o' the Times" album. The third song released on streaming services to preview the package, this 5 1/2-minute song is one of 45 previously unreleased studio tracks in the boxed set.

Long a coveted rarity, "Cosmic Day" is a supersized slice of paisley-infused psychedelia featuring Prince's "Camille" voice (electronically pitched to sound like a cartoonish female voice) and some nifty guitar work that would make Journey's Neal Schon proud. The lyrics talk about a dream in which mermen are swimming up in the sky. Cosmic, indeed.

"Cosmic Day" was recorded Nov. 15, 1986, at Sunset Sound in Los Angeles.

The reissue of 1987's "Sign o' the Times," arguably Prince's best studio album, is set for Sept. 25.

Warner Bros. has baited with two other songs from the project – a 1979 version of "I Could Never Take the Place of Your Man" (a song featured on "Sign o' the Times") and "Witness 4 the Prosecution (Version 1)."

The super-deluxe boxed set contains 92 tracks and a live DVD of Prince's New Year's Eve 1987 concert at Paisley Park.

On Thursday, the Prince estate posted his handwritten lyrics to "Cosmic Day" on its social media accounts.