pebble

pebble
/ˈpebl; `pɛbl/ n
1 small stone made smooth and round by the action of water, eg in a stream or on the seashore 卵石; 砾石.
2 (idm 习语) not the only pebble on the beach not the only person who matters or who has to be considered 并非唯一要紧的或要考虑的人.

牛津英汉双解词典