Hail Mary Mallon is a collaborative project between rappers and producers Aesop Rock and Rob Sonic. Their first single under the name came on the “Definitive Jux Presents 4” compilation for the now-defunct Def Jux Records. Their first full release, entitled “Are You Gonna Eat That?” came in 2011. The follow-up, “Bestiary,” was released in November 2014.

Aesop Rock and Rob Sonic both hold themselves lyrically on “Bestiary.” Both rappers are known for a very abstract style, and that is clearly on display. Whether it’s Aesop telling the listener to “pick a wing and a prayer and a palmed crib sheet” on “Krill” or Rob saying “circusing his Burger King sesame seed bun, Fred parry berry with the Weatherby re-runs” on “Hang Ten,” it will take you a lot of time on Google to figure out what they are actually saying, and catch every reference.

The pair also has great chemistry on the mic. They’re often finishing each other’s lines or picking up a reference the other started. For instance on the lead single “Johnathan,” Aesop ends a verse with a reference to Billy Joel’s “Downeaster Alexa,” while Rob starts his with an allusion to “We Didn’t Start the Fire.”

A lot of very different topics are covered on “Bestiary,” from absurd to very deep. On “Jonathan,” the two have braggadocious verses. While on “Kiln,” Rob talks about violence, and Aesop talks about isolation. “Whales” is a satirical song about spending money, while “Dollywood” is about their underground fame in the rap world, and how they’re happy to have it. Throughout the entire album, there is a tongue in cheek narrative about Hail Mary Mallon having a fundraiser concert to re-open a bowling alley, but it is reduced to short skits at the end of some songs.

The beats on “Bestiary” are some of the most hard-hitting either of them has rapped on. A lot of them follow a basic pattern; pounding drums, deep bass lines, and scratches by DJ Big Wiz. It does not get tiring throughout the album though. “Jonathan” uses the formula to create a beat that invokes old-school hip-hop ciphers, while “Dollywood” sounds like a rock-inspired Bollywood movie soundtrack. “Whales” sounds like a song by noise-hop group Clipping. The style of the beats is reminiscent of Aesop Rock’s 2012 solo effort “Skelethon.” Mostly produced by Aesop Rock (save for four that are produced by Rob Sonic), the beats support the duo’s lyricism well without getting too boring. Overall, Bestiary is a great example of what happens when two great rappers collaborate. Aesop and Rob’s styles perfectly complement each other over fantastic beats.

Aesop Rock and Rob Sonic will appear at the Sinclair in Cambridge on February 17 w/Homeboy Sandman.