I would support your idea that you might have been looking at an aquatic
insect.  For ex, the larva of psephenid beetles cling to the under surface
of stones and are called "water pennies" -- however they do not have a
snail-like foot on their undersurface.

Joan Jass, Invertebrate Zoology, Milwaukee Public Museum

At 11:25 AM 10/01/2001 -0600, you wrote:
>Good day Conchlers,
>
>I've had a family from NJ, USA  approach me with the following query:
>
>"Today (Sunday the 30th)  we were in a fresh water brook (about 6 inches of
>water).  We were turning over rocks and found a number of creatures (what
>appeared to be baby  hellbenders, crawfish, caddis, etc.) and affixed to
>several flat rocks we found what appear to be chitons.  Now from what we
>have read they (chitons) are  marine animals.  I understand marine to mean
>salt water.  They also did not  curl up when detached from the rock.  Do you
>have any idea what they might be?
>
>Kathy C. Cornetto who has exhausted our extensive library
>email:  [log in to unmask] "
>
>I asked Kathy if she had a picture of the critter in question and in
>response she went on to say:  "Sorry even with my macro zoom lens I don't
>think I'd get a very good shot as it is about 1/2 to 1 cm in length.  I'm
>beginning to wonder if it could have been some type of aquatic insect but I
>don't think so.  It seemed to look like a ovalish limpet & seemed to have
>what looked like snail's foot (minus the door) underneath. "
>
>If you can be of any help and wish to answer directly to Kathy (and her
>kids), please be sure to use the  words "Mysterious Critter"  in the subject
>line as Kathy receives a few hundred emails per day and she doesn't want
>delete answers to this question  accidentally.  If you wish to reply to the
>group, I will pass the answers on to Kathy personally.
>
>I thank you for helping out on this query that I am not able to answer.
>
>All the best,
>
>Avril Bourquin
>P.O.Box 366
>Invermere, British Columbia
>Canada
>V0A 1K0
>
>Phone: (250) 342-7224
>EMail:  [log in to unmask]
>URL:  www.manandmollusc.net
>