Clam experts: any thoughts on how old my T. Squamosa might be?

Unfortunately, I don't think anyone can accurately estimate how old your clam is. There are a few reasons for this. Closed marine systems are relatively unstable when compared to wild marine environments. (Excluding contamination and pollution by humans and temp. fluctuations due to El Nino)

Fluctuating elements, especially Ca, will dramatically affect the growth rate of your clam. Likewise, higher than natural nitrate and phosphate levels will increase shell growth rates unnaturally. All of these fluctuations take place in closed systems.

We do not know how long your squamosa has lived in captivity away from the ocean.

I can however, speculate on its age using information we do know. Squamosas are an intermediate species with regard to tridacnid growth rates. They are not "slow growers" like croceas, and they are not the "beasts of growth" we call derasa and gigas.

So, assuming normal growth rate in a stable marine environment, I estimate your clam to be somewhere in the range of 10 years old or so. This is a very general conservative guesstimate, but certainly he could have existed much longer than this because a 12" squamosa is reaching the edge of its maximum size. Growth rates would be much slower at this age, if he is adding new shell at all.

I would not be surprised if he reached 14" or 15", but from here on out is really an unknown. Assuming nothing happens to your clam he should live another 20 years or so with no problem.
Thanks for the input, cromax. I read in one {most likely unreliable} reference book that T. squamosa might approach 24" in length when fully grown. Can anyone confirm this?
I just checked Knop's book. He said that they reach... "shell lengths of 30cm, occasionally even 40cm." (pg. 22, Knop) So, we are looking at a max size of 11.8 to 15.7 inches. :bigeyes:
FWIW, without predation, or other environmental factors some animals have longer lifespans in captivity than in the wild. Assuming a clam grows it's entire life, it may be possible that captive clams can grow larger than their wild brethren.
I also have a 12" squamosa or 'fluted clam' named because of the side flutes on the shell. It opens to about 14-16". The clam was purchased at 3" eight years ago and has about 10 flutes now. So, that is roughly 1 flute per year. Of course shell growth rate is probably a very complex formula involving light, Ca/Mg levels, etc but maybe you could guestimate using flutes? :D

cromax: Good guess! That is about how old my 12" squamosa is.

gary: how many flutes does your clam have?

plankton, I got out the flashlight {It's 1 AM!} and looked at the scutes. I see that my clam is working on completing scute #8. Perhaps it's aprox. 8 years old?