I believe some of Bill Kier's students have found basic capability for abstract concepts in octopi.  Specifically, the octopus was able to learn to select the different item out of a set of choices, which requires having some concept of "different".

Giant clams are able to learn in a very limited way.  A shadow passing over will cause them to retract.  However, a repeated pattern (e.g., a scientist trying in the lab to replicate the effect of a floating object moved by waves) will eventually be ignored.

    Dr. David Campbell
    Old Seashells
    University of Alabama
    Biodiversity & Systematics
    Dept. Biological Sciences
    Box 870345
    Tuscaloosa, AL  35487 USA
    [log in to unmask]

That is Uncle Joe, taken in the masonic regalia of a Grand Exalted Periwinkle of the Mystic Order of Whelks-P.G. Wodehouse, Romance at Droitgate Spa