If I had more of a context to put it in I could give you a more specific asnwer about what it means to you. Fortunately for you interpreting dreams is something I have a bit of a knack for.
The general meaning of turtles (all turtles) is deffensiveness. The turtle is a shy, slow animal - that represents caution. It also tends to hide in its shell whenever confronted by danger - not so much cowardly as non-confrontational. The hiding in the shell part can also represent a person who's socially inept. Not to the point of reclussion necessarily, just being social tends to be stressful. On the plus side its slow nature represents a mellow characterist. Since many turtles can live for a long time they can also represent wisdom, and longevity. Somewhere I had an interpretation from a native American perspective but I can't recall it or just mentioned it and didn't even realize it.
Like I said its all about context.
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