Plural -o

Nouns ending in -o can add either -s or -es in the plural, and some can be spelled either way.

potato - potatoes

tomato - tomatoes

buffalo - buffaloes

domino - dominoes

mosquito - mosquitoes

but

studio - studios

solo - solos

zoo - zoos

embryo - embryos

and

flamingo - flamingos - flamingoes

tornado - tornados - tornadoes

mango - mangos - mangoes

fresco - frescos - frescoes

volcano - volcanos - volcanoes