hmmmm....fishy check-raise

[A_PLUS]

Empire 5k. Little under 100 left. For some reason our table has been 7 handed for a while. Table is passive, 1 shortie, me 1500, and 5 guys in the 2500-3500 range who look happy to preserve their stacks for a while.

I am raising about 30% of my hands. Built my stack from 1100 without showing down, needless to say, my image is that of an over-aggressive donk (so pretty much spot on).

I raise from CO with 94o. to 2.75xBB. Passive BB calls (has done this and folded to 1/2 cont bets twice).

Flop 7c, 9c, Ts

He checks, I bet 125 into a 185 chip pot.

He check raises me to 700??????

At a 25$ MTT, this usually means:
-Any Ace. He decided to make his stand with a CR before the flop.
-OP that is afraid of the flush draw
-Low-Mid PP, figures flop missed me.
-Flush draw, OE SD
-Maybe weaker T (JT, QT)

Any thoughts? I dont think it is an easy fold, BTW