I have a clam in room B360.

Every now and again it pokes it foot out. If you move the beaker, it pulls it right back in again.

The students are fascinated. A live clam in their class. Imagine that. While it's a little disheartening that a clam's foot can compete with my, um, well-crafted lesson plans, I put up with its insouciance.

Descent with modification led to this--a clam in a beaker with a strip of elodea, me with a laser pointer and a sometimes functioning SMART Board. Both of us are out of our elements. My hands are designed to pick basil seeds. The clam's foot is designed to pull itself deeper into the mud.

Descent with modification. To call it "evolution" presupposes I am more perfect than my shelled classroom buddy. Neither one of us is enhancing our reproductive strategies in B360. Neither one of us is particularly fit for our new environment.

In class we both lack purpose--no seeds to cull, no mud to muck in. Neither of us will last more than a lifetime. I was planning to eat the clam at the end of the school year.

I can't. Come next June Mr. Clam will be back in wild water, sowing his oats. I'll be back in my garden, sowing mine. And a few of my kids will remember the tentative foot of a clam during science class decades after memories of covalent bonds fade from their lives.