The following unanswered e-mail, sent 6-14-08, sums up my experience pretty well:
"Our order was received and I must say I'm very disappointed. Getting Azolla has been a real problem this year. We ordered three portions from the Mega Pond Store and received a bag containing enough to completely cover the surface of at least two 100 gallon tubs. Unfortunately it was duck weed rather than azolla and the company chose to refund our money when we complained rather than to ship what we ordered. The three portions from your company cover perhaps 1 square foot of one tub and at this point the plants are not well enough developed to tell if they are azolla or not. They look more like something that should be skimmed off than like something that might grow.
Have had Hydrocharis morsus-ranae for years, which is what I ordered, but none of it survived last winter when we decided to leave it outside rather than fight aphids on it all winter inside. Have no idea what the plant you sent is but it isn't Hydrocharis (flowering frogbit). Although the leaves are roughly the proper shape they lack the floating sacs of frogbit , the plants are many times too large and obviously need to be potted rather than expected to float.
Given this years experience, and having tropical water lilies other than what we ordered shipped to us last year from another company, we are about ready to stop ordering on line, by phone or by mail from any company we have not dealt with for years."
Since sending the above e-mail some of the Azolla (about enough to hold in the palm of a hand) has filled out enough to be recognizable but; given what I paid, the price was exorbitant. Haven't done the math but the price / ounce is probably comparable to that of gold.