Roberta prepares to swim

Que Linda sneaking up on Phil

Stacy and Linda - from Que Linda

Hal's son Chris, from Que Linda

Linda and Stacy (from Que Linda) - after diving from above Sans Souci

Michael Ronquillo - EMT aboard Sans Souci

Grey Pearl, Goleen and Que Linda

While swimming, we encounted this "thing." At first everyone convinced themselves that it was just seaweed, then we decided that it was alive. Does anyone know what it is (was)? I think I remember seeing something similar in the first Alien film.