Sitting on santa monica state beach, first noticed silvery object directly abeam the beach moving slowly left to right, constant elevation. disappeared after about 3-4 seconds. reappeared a few seconds later but to the left of where it disappeared, opposite the direction it was moving! was again moving left to right and disappeared again after a few seconds. this sequence repeated several times, maybe half a dozen times. the reappearances were not to the same spot in the sky. the last time i saw it was about 6 minutes after the first time and was the longest duration sighting, over 5 seconds. a second member of our group also saw it after i pointed it out, so it wasn't an anomaly with my sunglasses. weather was sunny, high thin cirrus, winds onshore at probably 10 kts.