expression, noun
Refers to the dark liquid produced by squid, used in cooking (e.g., pasta, risotto) or as a defense mechanism.
See also: イカ墨
イカの墨を使ったパスタが好きです。
I like pasta made with squid ink.
イカは危険を感じると
When a squid senses danger, it squirts out squid ink.
イカ墨 is a compound noun often used attributively (e.g., イカ墨パスタ), while イカの墨 is a phrase that explicitly means 'squid's ink'.
Compound of イカ (squid) + の (possessive particle) + 墨 (ink).