An odd flower formed around the main leading shoot of a tomato plant. With rather more than the normal number of petals, it completely surrounded the main leading shoot, with a tuft of leaves sticking out of the middle. A deformed tomato (with irregular deep ribbing) has now formed there, with a tuft of leaves sticking out from the end of it. But the leader is not growing any more, and the whole plant has not gained in height. It hasn't produced any other flowers.

Is this a common phenomenon? Would it be any better if we cut off the freak tomato? Or should I just wait and enjoy the one tomato this plant looks like it will produce?