Went to the beach today and despite the legal technicalities I may have crossed I picked up a few periwinkles off the shore (I think that's what they're called- it's the "cone/oval" shaped shells that burry themselves into the sand) and a few live rocks-I think it's live rock but if not then its super eroded rock and has a lot of holes therefore providing more surface area so wouldn't it act like live rock? My question is is it ok to put these in the tank or any wild caught creatures?