I was supposed to receive a Pygmy/Dwarf species of octopus from my LFS. He looked like one at the store, but as soon as he got in the tank and spread his legs...uh-oh. A bit larger than expected. I have gotten a good opinion that believes it may be the O. briareus species. I don't know much about them to agree or disagree, but the different coloration and lack of that "irridescence" makes me wonder. Thanks for any help here! Side note: I have a 36 gallon tank, so if it is a briareus, he will have to be returned the ocean at some point :[ Mantle: About 1.5 inches Arm tip to Arm tip: Around 7-8 inches. I haven't been able to measure since the 1st day, but when he slinks up the sides I can tell they are longer than the original 6 in. that I measured.