Free-agent defensive tackle Sedrick Ellis visited both the Detroit Lions and Chicago Bears last week. The Lions hosted him in hopes of potentially adding extra depth at defensive tackle, but they will have to take their search elsewhere. I say that because Ellis has agreed to a one-year deal with the Bears, according to Adam Schefter.
With Ellis headed to Chicago instead of Detroit, the Lions still have only five defensive tackles on their roster. Ndamukong Suh and Nick Fairley are the starters, and they very well may be the best defensive tackle tandem in all of the NFL. In that regard, the Lions are absolutely set at defensive tackle.
Behind Suh and Fairley on the depth chart are C.J. Mosley, Ogemdi Nwagbuo and Jimmy Saddler-McQueen. Mosley was added in April as the Lions' top backup at the position, whereas Nwagbuo and Saddler-McQueen are back after joining the team toward the end of last season. They will battle it out for the last spot at defensive tackle unless the Lions decide to sign somebody else.
One idea that has been mentioned here several times is to re-sign Corey Williams, who spent the last three seasons with the Lions. Williams visited the Oakland Raiders back in March, but there hasn't been any news on him since then. Perhaps he's simply not healthy right now, but I think he'd be worth a look if injuries aren't a concern.