chacalin.

Headword: 
chacalin.
Principal English Translation: 

a large shrimp (see Molina); a small shrimp; a freshwater shrimp; a red or white shrimp; a crayfish; sometimes also translated as crab; sometimes a nickname for a boy (to get these many translations, Google "chacalin")

Orthographic Variants: 
chacalli, chacallin, chacalatl
Alonso de Molina: 

chacalin. camaron grande.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 18v. col. 2. Thanks to Joe Campbell for providing the transcription.

Attestations from sources in English: 

chacalcozcatl = shrimp necklaces
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 10 -- The People, No. 14, Part 11, eds. and transl. Arthur J. O. Anderson and Charles E. Dibble (Santa Fe and Salt Lake City: School of American Research and the University of Utah, 1961), 61.