giant clam

i think my clam is dying
ive had him for and he's been fine until now
his shell is almost totally closed and he looks like he's all shriveled up
all the water parameters test out fine, calcium is fine, and the everything else looks healthy
what is the lifespan on giant clams anyway

easily 100 years

Have you checked for stray voltage? Also check out the mantel very carefully and the shell. There are few clam parasites that can cause the symptoms you are describing

how can i check for stray voltage?

Identifying, Locating and Curing Stray Voltage in a Saltwater Aquarium

Re-check water parms! Are you sure trates are low? No copper?

Were the Byssal threads damaged? Did you try to move it recently? Otherwise go with Sen's and little fishes suggestions

What kind of lighting do you have? How is your calcium?

Sounds like his foot may have been torn, from something moving him.

Also check for Brissil worms ..they can eat the foot off of clams and destroy the clams mantle. Also do you feed your clam? phytoplankton ? Add calcium ?

Clams larger than about 2-2.5 inches do not need to be fed, they get everything they need photosynthetically

Have you noticed anything picking on or harrassing the clam?