Lomanotus vermiformis is a species of sea slug, a marine gastropod mollusk in the family Lomanotidae.

[2] The specific name vermiformis is from Latin language and it means "in the shape of a worm" referring to elongate body of this species.

[4] Minimum recorded depth is 1 m.[6] Maximum recorded depth is 4.5 m.[6] Lomanotus vermiformis feeds on the common stinging hydroid Lytocarpus philippinus[4] and on hydroids of the genus Macrorhynchia.

[5] It was also found feeding on an unidentified species of hydroid in Panama, on which it is extremely cryptic.

[5] Lomanotus vermiformis can swim with lateral flexions of the body when disturbed.