I was brought up partly in Morriston, Plas y Coed, from the end of the war to the mid fifties. The road at the foot of the hill in front of our terrace is Pentremalwed Road, but my grandmother always said the name was to do with snails. Pentremalwod (snail village) does appear in archives for what is now Clyndu St, nearby, but not on that exact street - has anyone got any historic maps of that area? I did some family research and found that there was tram road along what is now Pentremalwed Road, the one I'm writing about, as well as a tram road down what is now Clyndu Street.
Maybe by the time Pentremalwed Road got its name no-one wanted it be linked with snails.
There is a word "malwod" which does indeed mean snails or slugs. Why it should be attributed to Pentremalwod beats me.
Clyndu Street ran from the Duke up to at least the "Prince" and Pentremalwod Road ran behind Clyndu Street and parallel with it At the top end of Morfydd Street Crossed Clyndu Street and Pentremalwod Street started at the top of Morfydd SDtreet.
i've alwaysed pronounced it Pentremalwed Road though.
malwod - snails (standard Welsh)
malwed - snails (West Glamorgan, Carmarthenshire, parts of Ceredigion)
See Geiriadur Prifysgol Cymru / University of Wales Dictionary under malwod.