Drain Rats are what you tug up out of the shower drain when you finally buckle down to give it a good clean. Be prepared for an ugly, stomach-turning blob of goo that has collected over the last three years or however long you've neglected the job.
Drain Mice are the smaller species of similarly disgusting material, maybe four years in collecting, that have amassed in the drain of your bathroom sink.
My sister and I made a pact to clean our houses separate bathroom sinks a few days ago. She got her's done right away. I left mine to one of the Things I Get to Do Today. With the help of wrenches, boiling water, baking soda, vinegar, rags, brushes, picks and rubber gloves (Oh, please do NOT forget the gloves!) the slimy mouse is gone. The sink drain is clean. The water slips down and out with ease. I conquered the monster. You can, too! I'm sipping ginger ale--my stomach will be recovered by the time you read this