Kappaphycus alvarezii, also known as Elkhorn sea moss, is a red alga. This seaweed is rich in carrageenans - natural linear sulfated polysaccharides, with excellent gel-forming and film-forming (after application) properties.

Carrageenan forms a veil on the skin surface, reducing transdermal water loss and desquamation. Even from the first application of a formulation with Elkhorn sea moss extract, it smooths fine lines, furrows, and deep wrinkles, revealing lifted, fine, and supple surfaces.

Elkhorn sea moss extract contains natural antioxidants that protect skin from UV-induced damage and oxidative stress.

Kappaphycus alvarezii extract may form a hydrogel with a glycosaminoglycan-like (GAG-like) structure similar to skin extracellular matrix that speeds up the wound healing process, moisture deposition and reduce inflammation or irritation.
https://inci.guide/marine-extracts/kappaphycus-alvarezii-extract

This ingredient is not currently on EWG's Skin Deep Restricted or Unacceptable Lists.
https://www.ewg.org/skindeep/ingredients/720092-KAPPAPHYCUS_ALVAREZII_EXTRACT/