Coach Cam Cameron confirmed on Monday that Bell sustained an Achilles injury, although he wouldn't specify whether the Achilles was torn.
Regardless, Bell is done for the season, and the Dolphins now have to figure out what to do in the secondary.
Travares Tillman, who started last season before being replaced in the lineup by Bell, figures to take over as the starting safety alongside Renaldo Hill.
Another potential consequence of Bell's injury could be that 2006 first-round pick Jason Allen could go back to safety. That's the position Allen played last year before he was switched this offseason.
Cameron said a decision on how to compensate for Bell's absence would be made in the next couple of days.
For Bell, this was just another bad break in a career that's starting to have too many of them.
As a rookie in 2003, Bell broke an ankle while he was on the practice squad. He played the first 13 games the following season before fracturing his right tibia.
Bell played all 16 games in a reserve role in 2005 and moved into the starting lineup in the sixth game of the 2006 season.
Not coincidentally, the Dolphins defense really picked up its game after the athletic and aggressive Bell moved into the starting lineup last year.
Now, the Dolphins will have to make do without him, and that's clearly a blow for the defense.