Jellyfish, sharks, dolphins, turtles, eels and even crocodiles were spotted by visitors to Blackpool Beach.
But holidaymakers had no cause for alarm as these creatures were made out of sand.
They were created by youngsters as part of a sand sculpture competition organised by the Lancashire Wildlife Trust.
Sharky, from the Blackpool Sea Life Centre, decided upon the winners and awarded first prize to the turtle and boat made by Leoni McFadden, 11, from Paisley, in Scotland.
Leoni got a little help from her dad Philip, who is likely to claim the prize of swimming with sharks at the promenade attraction, but the whole family will be able to go along to watch.
Winners of the children’s category was Jaydon Murphy, four, from Blackpool, who created a jellyfish and fish.
Jaydon, who was helped by mum Toni, won a family ticket to the Blackpool Sea Life Centre.
Alan Wright, the trust’s senior communications and campaigns officer, said: “It was really, really difficult to choose a winner because there were some fabulous sand sculptures.
“It’s just a shame they will be washed away at high tide.
“What was amazing was to see that the children and their families do have a real knowledge of what is in the seas around the UK.
“To have children creating basking sharks, turtles and jellyfish is really heartening.”
The competition was organised to help raise awareness of the wildlife inhabiting the Irish Sea as part of the trust’s Marine Week.
A 100-square-mile Marine Conservation Zone was recently designated off the Fylde coast.