Rinsing LECA... safe for bathtub drain?

[ALToronto]

A p-trap is the U-shaped bend in the drain pipe under the sink. I don't know why it's not called a U-trap. To remove it, undo the threads at both ends.

It keeps sewer smells from getting into your home, and it also traps debris that might go down the drain. If you ever drop a ring in the sink, it will stay in the p-trap, and you will be able to retrieve it.