"Michael has played very well against the Ravens, so we know firsthand the attributes he brings to the game", Newsome said in a team statement.
Crabtree spent the past three seasons with the Oakland Raiders, emerging as quarterback Derek Carr's most consistent threat on the outside. The NFL Network reported the deal to be worth $21 million, with $11 million guaranteed.
Jimmy's Seafood, however, extended their usual offer of crab cakes for life.
The 6-1, 215-pounder has totaled at least 85 catches in a season three times, with a career-high 89 during the 2016 campaign. In five career games against the Ravens, including the Super Bowl with the San Franciso 49ers, Crabtree has 33 catches for 444 yards and six touchdowns.
After allowing Donte Moncrief to walk into free agency - and then signing with the Jacksonville Jaguars - the Colts will be in the market for a wide receiver and Grant is reportedly on the docket for a visit.
The wide receiver played for the 49ers from 2009-14. Crabtree and Steelers WR Antonio Brown are the only National Football League players to post at least eight touchdown catches in each of the past three seasons.
The Ravens are looking to improve their receivers for quarterback Joe Flacco after ranking No. 29 in passing last season.
Crabtree is a big addition for Baltimore's franchise.
Astronaut Scott Kelly's DNA Changed in Space
Because of the change, Kelly and his brother-retired astronaut Mark Kelly-are no longer considered identical twins. Last year, NASA published its first round of preliminary results at the 2017 Investigator's Workshop.